Extract array of objects based on their content - javascript

In JavaScript I have a JSON array like this:
var r = [{"name":"a","bool":false},{"name":"b","bool":false},
{"name":"c","bool":false},{"name":"a","bool":false},
{"name":"b","bool":false},{"name":"c","bool":true},
{"name":"a","bool":true}];
I want to build another array containing all the objects where name=="a" and bool==false. I solved this by looping, but I wanted to know if there is another way to do it.
How can I do?
[edit]
My loop was:
var rLen = r.length;
var newArray = [];
for(var i=0;i<rLen;i++) {
if(r[i].name=="a"&&r[i].bool==false) {
newArray.push(r[i]);
}
}

In the end it will always be solved by loops internally, e.g.
var r = [{"name":"a","bool":false},{"name":"b","bool":false},
{"name":"c","bool":false},{"name":"a","bool":false},
{"name":"b","bool":false},{"name":"c","bool":true},
{"name":"a","bool":true}];
var result = r.filter(function(item){
return item.name === 'a' && !item.bool;
});
If you look at the polyfill, you'll notice the loop:
if (!Array.prototype.filter) {
Array.prototype.filter = function(fun/*, thisArg*/) {
'use strict';
if (this === void 0 || this === null) {
throw new TypeError();
}
var t = Object(this);
var len = t.length >>> 0;
if (typeof fun !== 'function') {
throw new TypeError();
}
var res = [];
var thisArg = arguments.length >= 2 ? arguments[1] : void 0;
for (var i = 0; i < len; i++) { // <--
if (i in t) {
var val = t[i];
// NOTE: Technically this should Object.defineProperty at
// the next index, as push can be affected by
// properties on Object.prototype and Array.prototype.
// But that method's new, and collisions should be
// rare, so use the more-compatible alternative.
if (fun.call(thisArg, val, i, t)) {
res.push(val);
}
}
}
return res;
};
}
Since you're interested in performance, here is a jsperf comparing the two: http://jsperf.com/aarontgrogg-array-filter-vs-for-loop

may be
var r1 = r.filter(function(item){ return item.name === "a" && !item.bool; });

Related

Compare two objects based on property names [duplicate]

I am using node, mocha, and chai for my application. I want to test that my returned results data property is the same "type of object" as one of my model objects (Very similar to chai's instance). I just want to confirm that the two objects have the same sets of property names. I am specifically not interested in the actual values of the properties.
Let's say I have the model Person like below. I want to check that my results.data has all the same properties as the expected model does. So in this case, Person which has a firstName and lastName.
So if results.data.lastName and results.data.firstName both exist, then it should return true. If either one doesn't exist, it should return false. A bonus would be if results.data has any additional properties like results.data.surname, then it would return false because surname doesn't exist in Person.
This model
function Person(data) {
var self = this;
self.firstName = "unknown";
self.lastName = "unknown";
if (typeof data != "undefined") {
self.firstName = data.firstName;
self.lastName = data.lastName;
}
}
You can serialize simple data to check for equality:
data1 = {firstName: 'John', lastName: 'Smith'};
data2 = {firstName: 'Jane', lastName: 'Smith'};
JSON.stringify(data1) === JSON.stringify(data2)
This will give you something like
'{firstName:"John",lastName:"Smith"}' === '{firstName:"Jane",lastName:"Smith"}'
As a function...
function compare(a, b) {
return JSON.stringify(a) === JSON.stringify(b);
}
compare(data1, data2);
EDIT
If you're using chai like you say, check out http://chaijs.com/api/bdd/#equal-section
EDIT 2
If you just want to check keys...
function compareKeys(a, b) {
var aKeys = Object.keys(a).sort();
var bKeys = Object.keys(b).sort();
return JSON.stringify(aKeys) === JSON.stringify(bKeys);
}
should do it.
2 Here a short ES6 variadic version:
function objectsHaveSameKeys(...objects) {
const allKeys = objects.reduce((keys, object) => keys.concat(Object.keys(object)), []);
const union = new Set(allKeys);
return objects.every(object => union.size === Object.keys(object).length);
}
A little performance test (MacBook Pro - 2,8 GHz Intel Core i7, Node 5.5.0):
var x = {};
var y = {};
for (var i = 0; i < 5000000; ++i) {
x[i] = i;
y[i] = i;
}
Results:
objectsHaveSameKeys(x, y) // took 4996 milliseconds
compareKeys(x, y) // took 14880 milliseconds
hasSameProps(x,y) // after 10 minutes I stopped execution
If you want to check if both objects have the same properties name, you can do this:
function hasSameProps( obj1, obj2 ) {
return Object.keys( obj1 ).every( function( prop ) {
return obj2.hasOwnProperty( prop );
});
}
var obj1 = { prop1: 'hello', prop2: 'world', prop3: [1,2,3,4,5] },
obj2 = { prop1: 'hello', prop2: 'world', prop3: [1,2,3,4,5] };
console.log(hasSameProps(obj1, obj2));
In this way you are sure to check only iterable and accessible properties of both the objects.
EDIT - 2013.04.26:
The previous function can be rewritten in the following way:
function hasSameProps( obj1, obj2 ) {
var obj1Props = Object.keys( obj1 ),
obj2Props = Object.keys( obj2 );
if ( obj1Props.length == obj2Props.length ) {
return obj1Props.every( function( prop ) {
return obj2Props.indexOf( prop ) >= 0;
});
}
return false;
}
In this way we check that both the objects have the same number of properties (otherwise the objects haven't the same properties, and we must return a logical false) then, if the number matches, we go to check if they have the same properties.
Bonus
A possible enhancement could be to introduce also a type checking to enforce the match on every property.
If you want deep validation like #speculees, here's an answer using deep-keys (disclosure: I'm sort of a maintainer of this small package)
// obj1 should have all of obj2's properties
var deepKeys = require('deep-keys');
var _ = require('underscore');
assert(0 === _.difference(deepKeys(obj2), deepKeys(obj1)).length);
// obj1 should have exactly obj2's properties
var deepKeys = require('deep-keys');
var _ = require('lodash');
assert(0 === _.xor(deepKeys(obj2), deepKeys(obj1)).length);
or with chai:
var expect = require('chai').expect;
var deepKeys = require('deep-keys');
// obj1 should have all of obj2's properties
expect(deepKeys(obj1)).to.include.members(deepKeys(obj2));
// obj1 should have exactly obj2's properties
expect(deepKeys(obj1)).to.have.members(deepKeys(obj2));
Here's a deep-check version of the function provided above by schirrmacher.
Below is my attempt. Please note:
Solution does not check for null and is not bullet proof
I haven't performance tested it. Maybe schirrmacher or OP can do that and share for the community.
I'm not a JS expert :).
function objectsHaveSameKeys(...objects) {
const allKeys = objects.reduce((keys, object) => keys.concat(Object.keys(object)), [])
const union = new Set(allKeys)
if (union.size === 0) return true
if (!objects.every((object) => union.size === Object.keys(object).length)) return false
for (let key of union.keys()) {
let res = objects.map((o) => (typeof o[key] === 'object' ? o[key] : {}))
if (!objectsHaveSameKeys(...res)) return false
}
return true
}
Update 1
A 90% improvement on the recursive deep-check version is achieved on my computer by skipping the concat() and adding the keys directly to the Set(). The same optimization to the original single level version by schirrmacher also achieves ~40% improvement.
The optimized deep-check is now very similar in performance to the optimized single level version!
function objectsHaveSameKeysOptimized(...objects) {
let union = new Set();
union = objects.reduce((keys, object) => keys.add(Object.keys(object)), union);
if (union.size === 0) return true
if (!objects.every((object) => union.size === Object.keys(object).length)) return false
for (let key of union.keys()) {
let res = objects.map((o) => (typeof o[key] === 'object' ? o[key] : {}))
if (!objectsHaveSameKeys(...res)) return false
}
return true
}
Performance Comparison
var x = {}
var y = {}
var a = {}
for (var j = 0; j < 10; ++j){
a[j] = j
}
for (var i = 0; i < 500000; ++i) {
x[i] = JSON.parse(JSON.stringify(a))
y[i] = JSON.parse(JSON.stringify(a))
}
let startTs = new Date()
let result = objectsHaveSameKeys(x, y)
let endTs = new Date()
console.log('objectsHaveSameKeys = ' + (endTs - startTs)/1000)
Results
A: Recursive/deep-check versions*
objectsHaveSameKeys = 5.185
objectsHaveSameKeysOptimized = 0.415
B: Original non-deep versions
objectsHaveSameKeysOriginalNonDeep = 0.517
objectsHaveSameKeysOriginalNonDeepOptimized = 0.342
function getObjectProperties(object, propertiesString = '') {
let auxPropertiesString = propertiesString;
for (const objectLevel of Object.keys(object).sort((a, b) => a.localeCompare(b))) {
if (typeof object[objectLevel] === 'object') {
auxPropertiesString += getObjectProperties(object[objectLevel], auxPropertiesString);
} else {
auxPropertiesString += objectLevel;
}
}
return auxPropertiesString;
}
function objectsHaveTheSameKeys(objects) {
const properties = [];
for (const object of objects) {
properties.push(getObjectProperties(object));
}
return properties.every(eachProperty => eachProperty === properties[0]);
}
It's a bit rudimentary, but should do the work in case you want to compare properties.
Legacy Browser Object Compare Function
Unlike the other solutions posted here, my Object Compare Function works in ALL BROWSERS, modern or legacy, including very old browsers, even Internet Explorer 5 (c.2000)!
Features:
Can compare an unlimited list of Objects. All must match or fails!
Ignores property order
Only compares "own" properties (i.e. non-prototype)
Matches BOTH property names and property values (key-value pairs)!
Matches functions signatures in objects!
Every object submitted is cross-compared with each other to detect missing properties in cases where one is missing but not in the other
Avoids null, undefined, NaN, Arrays, non-Objects, etc.
{} empty object detection
Works in almost ALL BROWSERS, including even Internet Explorer 5 and many other legacy browsers!
Note the function does not detect complex objects in properties, but you could rewrite the function to call them recursively.
Just call the method with as many objects as you like!
ObjectCompare(myObject1,myObject2,myObject3)
function ObjectCompare() {
try {
if (arguments && arguments.length > 0) {
var len = arguments.length;
if (len > 1) {
var array = [];
for (var i = 0; i < len; i++) {
if (
((typeof arguments[i] !== 'undefined') || (typeof arguments[i] === 'undefined' && arguments[i] !== undefined))
&& (arguments[i] !== null)
&& !(arguments[i] instanceof Array)
&& ((typeof arguments[i] === 'object') || (arguments[i] instanceof Object))
) {
array.push(arguments[i]);
}
}
if (array.length > 1) {
var a1 = array.slice();
var a2 = array.slice();
var len1 = a1.length;
var len2 = a2.length;
var noKeys = true;
var allKeysMatch = true;
for (var x = 0; x < len1; x++) {
console.log('---------- Start Object Check ---------');
//if (len2>0) {
// a2.shift();// remove next item
//}
len2 = a2.length;
if (len2 > 0 && allKeysMatch) {
for (var y = 0; y < len2; y++) {
if (x !== y) {// ignore objects checking themselves
//console.log('Object1: ' + JSON.stringify(a1[x]));
//console.log('Object2: ' + JSON.stringify(a2[y]));
console.log('Object1: ' + a1[x].toString());
console.log('Object2: ' + a2[y].toString());
var ownKeyCount1 = 0;
for (var key1 in a1[x]) {
if (a1[x].hasOwnProperty(key1)) {
// ---------- valid property to check ----------
ownKeyCount1++;
noKeys = false;
allKeysMatch = false;// prove all keys match!
var ownKeyCount2 = 0;
for (var key2 in a2[y]) {
if (a2[y].hasOwnProperty(key2) && !allKeysMatch) {
ownKeyCount2++;
if (key1 !== key1 && key2 !== key2) {// NaN check
allKeysMatch = true;// proven
break;
} else if (key1 === key2) {
if (a1[x][key1].toString() === a2[y][key2].toString()) {
allKeysMatch = true;// proven
console.log('KeyValueMatch=true : ' + key1 + ':' + a1[x][key1] + ' | ' + key2 + ':' + a2[y][key2]);
break;
}
}
}
}
if (ownKeyCount2 === 0) {// if second objects has no keys end early
console.log('-------------- End Check -------------');
return false;
}
// ---------------------------------------------
}
}
console.log('-------------- End Check -------------');
}
}
}
}
console.log('---------------------------------------');
if (noKeys || allKeysMatch) {
// If no keys in any objects, assume all objects are {} empty and so the same.
// If all keys match without errors, then all object match.
return true;
} else {
return false;
}
}
}
console.log('---------------------------------------');
return true;// one object
}
console.log('---------------------------------------');
return false;// no objects
} catch (e) {
if (typeof console !== 'undefined' && console.error) {
console.error('ERROR : Function ObjectCompare() : ' + e);
} else if (typeof console !== 'undefined' && console.warn) {
console.warn('WARNING : Function ObjectCompare() : ' + e);
} else if (typeof console !== 'undefined' && console.log) {
console.log('ERROR : Function ObjectCompare() : ' + e);
}
return false;
}
}
// TESTING...
var myObject1 = new Object({test: 1, item: 'hello', name: 'john', f: function(){var x=1;}});
var myObject2 = new Object({item: 'hello', name: 'john', test: 1, f: function(){var x=1;}});
var myObject3 = new Object({name: 'john', test: 1, item: 'hello', f: function(){var x=1;}});
// RETURNS TRUE
//console.log('DO ALL OBJECTS MATCH? ' + ObjectCompare(myObject1, myObject2, myObject3));
If you are using underscoreJs then you can simply use _.isEqual function
and it compares all keys and values at each and every level of hierarchy like below example.
var object = {"status":"inserted","id":"5799acb792b0525e05ba074c","data":{"workout":[{"set":[{"setNo":1,"exercises":[{"name":"hjkh","type":"Reps","category":"Cardio","set":{"reps":5}}],"isLastSet":false,"index":0,"isStart":true,"startDuration":1469689001989,"isEnd":true,"endDuration":1469689003323,"speed":"00:00:01"}],"setType":"Set","isSuper":false,"index":0}],"time":"2016-07-28T06:56:52.800Z"}};
var object1 = {"status":"inserted","id":"5799acb792b0525e05ba074c","data":{"workout":[{"set":[{"setNo":1,"exercises":[{"name":"hjkh","type":"Reps","category":"Cardio","set":{"reps":5}}],"isLastSet":false,"index":0,"isStart":true,"startDuration":1469689001989,"isEnd":true,"endDuration":1469689003323,"speed":"00:00:01"}],"setType":"Set","isSuper":false,"index":0}],"time":"2016-07-28T06:56:52.800Z"}};
console.log(_.isEqual(object, object1));//return true
If all the keys and values for those keys are same in both the objects then it will return true, otherwise return false.
Here is my attempt at validating JSON properties. I used #casey-foster 's approach, but added recursion for deeper validation. The third parameter in function is optional and only used for testing.
//compare json2 to json1
function isValidJson(json1, json2, showInConsole) {
if (!showInConsole)
showInConsole = false;
var aKeys = Object.keys(json1).sort();
var bKeys = Object.keys(json2).sort();
for (var i = 0; i < aKeys.length; i++) {
if (showInConsole)
console.log("---------" + JSON.stringify(aKeys[i]) + " " + JSON.stringify(bKeys[i]))
if (JSON.stringify(aKeys[i]) === JSON.stringify(bKeys[i])) {
if (typeof json1[aKeys[i]] === 'object'){ // contains another obj
if (showInConsole)
console.log("Entering " + JSON.stringify(aKeys[i]))
if (!isValidJson(json1[aKeys[i]], json2[bKeys[i]], showInConsole))
return false; // if recursive validation fails
if (showInConsole)
console.log("Leaving " + JSON.stringify(aKeys[i]))
}
} else {
console.warn("validation failed at " + aKeys[i]);
return false; // if attribute names dont mactch
}
}
return true;
}

Multiple conditions for one variable in 'if' condition. Javascript [duplicate]

This question already has answers here:
How do I check if an array includes a value in JavaScript?
(60 answers)
Closed 6 years ago.
I need to determine if a value exists in an array.
I am using the following function:
Array.prototype.contains = function(obj) {
var i = this.length;
while (i--) {
if (this[i] == obj) {
return true;
}
}
return false;
}
The above function always returns false.
The array values and the function call is as below:
arrValues = ["Sam","Great", "Sample", "High"]
alert(arrValues.contains("Sam"));
jQuery has a utility function for this:
$.inArray(value, array)
Returns index of value in array. Returns -1 if array does not contain value.
See also How do I check if an array includes an object in JavaScript?
var contains = function(needle) {
// Per spec, the way to identify NaN is that it is not equal to itself
var findNaN = needle !== needle;
var indexOf;
if(!findNaN && typeof Array.prototype.indexOf === 'function') {
indexOf = Array.prototype.indexOf;
} else {
indexOf = function(needle) {
var i = -1, index = -1;
for(i = 0; i < this.length; i++) {
var item = this[i];
if((findNaN && item !== item) || item === needle) {
index = i;
break;
}
}
return index;
};
}
return indexOf.call(this, needle) > -1;
};
You can use it like this:
var myArray = [0,1,2],
needle = 1,
index = contains.call(myArray, needle); // true
CodePen validation/usage
This is generally what the indexOf() method is for. You would say:
return arrValues.indexOf('Sam') > -1
Array.prototype.includes()
In ES2016, there is Array.prototype.includes().
The includes() method determines whether an array includes a certain element, returning true or false as appropriate.
Example
["Sam", "Great", "Sample", "High"].includes("Sam"); // true
Support
According to kangax and MDN, the following platforms are supported:
Chrome 47
Edge 14
Firefox 43
Opera 34
Safari 9
Node 6
Support can be expanded using Babel (using babel-polyfill) or core-js. MDN also provides a polyfill:
if (![].includes) {
Array.prototype.includes = function(searchElement /*, fromIndex*/ ) {
'use strict';
var O = Object(this);
var len = parseInt(O.length) || 0;
if (len === 0) {
return false;
}
var n = parseInt(arguments[1]) || 0;
var k;
if (n >= 0) {
k = n;
} else {
k = len + n;
if (k < 0) {k = 0;}
}
var currentElement;
while (k < len) {
currentElement = O[k];
if (searchElement === currentElement ||
(searchElement !== searchElement && currentElement !== currentElement)) {
return true;
}
k++;
}
return false;
};
}
It's almost always safer to use a library like lodash simply because of all the issues with cross-browser compatibilities and efficiency.
Efficiency because you can be guaranteed that at any given time, a hugely popular library like underscore will have the most efficient method of accomplishing a utility function like this.
_.includes([1, 2, 3], 3); // returns true
If you're concerned about the bulk that's being added to your application by including the whole library, know that you can include functionality separately:
var includes = require('lodash/collections/includes');
NOTICE: With older versions of lodash, this was _.contains() rather than _.includes().
Since ECMAScript6, one can use Set:
var myArray = ['A', 'B', 'C'];
var mySet = new Set(myArray);
var hasB = mySet.has('B'); // true
var hasZ = mySet.has('Z'); // false
tl;dr
function includes(k) {
for(var i=0; i < this.length; i++){
if( this[i] === k || ( this[i] !== this[i] && k !== k ) ){
return true;
}
}
return false;
}
Example
function includes(k) {
for(var i=0; i < this.length; i++){
if( this[i] === k || ( this[i] !== this[i] && k !== k ) ){
return true;
}
}
return false;
}
function log(msg){
$('#out').append('<div>' + msg + '</div>');
}
var arr = [1, "2", NaN, true];
arr.includes = includes;
log('var arr = [1, "2", NaN, true];');
log('<br/>');
log('arr.includes(1): ' + arr.includes(1));
log('arr.includes(2): ' + arr.includes(2));
log('arr.includes("2"): ' + arr.includes("2"));
log('arr.includes(NaN): ' + arr.includes(NaN));
log('arr.includes(true): ' + arr.includes(true));
log('arr.includes(false): ' + arr.includes(false));
#out{
font-family:monospace;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id=out></div>
Longer Answer
I know this question isn't really about whether or not to extend built-in objects, but the attempt of the OP and the comments on this answer highlight that debate. My comment from Feb 12, '13 cites an article that outlines this debate really well, however that link broke and I can't edit the original comment because too much time has passed, so I include it here.
If you're looking to extend the built-in Array object with a contains method, probably the best and most responsible way to do this would be to use this polyfill from MDN. (See also this section of the MDN article on Prototypical inheritance, which explains that "The only good reason for extending a built-in prototype is to backport the features of newer JavaScript engines; for example Array.forEach, etc.")
if (!Array.prototype.includes) {
Array.prototype.includes = function(searchElement /*, fromIndex*/ ) {
'use strict';
var O = Object(this);
var len = parseInt(O.length) || 0;
if (len === 0) {
return false;
}
var n = parseInt(arguments[1]) || 0;
var k;
if (n >= 0) {
k = n;
} else {
k = len + n;
if (k < 0) {k = 0;}
}
var currentElement;
while (k < len) {
currentElement = O[k];
if (searchElement === currentElement ||
(searchElement !== searchElement && currentElement !== currentElement)) {
return true;
}
k++;
}
return false;
};
}
Don't want strict equality, or want to choose?
function includes(k, strict) {
strict = strict !== false; // default is true
// strict = !!strict; // default is false
for(var i=0; i < this.length; i++){
if( (this[i] === k && strict) ||
(this[i] == k && !strict) ||
(this[i] !== this[i] && k !== k)
) {
return true;
}
}
return false;
}
My little contribution:
function isInArray(array, search)
{
return array.indexOf(search) >= 0;
}
//usage
if(isInArray(my_array, "my_value"))
{
//...
}
If you have access to ECMA 5 you can use the some method.
MDN SOME Method Link
arrValues = ["Sam","Great", "Sample", "High"];
function namePresent(name){
return name === this.toString();
}
// Note:
// namePresent requires .toString() method to coerce primitive value
// i.e. String {0: "S", 1: "a", 2: "m", length: 3, [[PrimitiveValue]]: "Sam"}
// into
// "Sam"
arrValues.some(namePresent, 'Sam');
=> true;
If you have access to ECMA 6 you can use the includes method.
MDN INCLUDES Method Link
arrValues = ["Sam","Great", "Sample", "High"];
arrValues.includes('Sam');
=> true;
Given the implementation of indexOf for IE (as described by eyelidlessness):
Array.prototype.contains = function(obj) {
return this.indexOf(obj) > -1;
};
You can use _.indexOf method or if you don't want to include whole Underscore.js library in your app, you can have a look how they did it and extract necessary code.
_.indexOf = function(array, item, isSorted) {
if (array == null) return -1;
var i = 0, l = array.length;
if (isSorted) {
if (typeof isSorted == 'number') {
i = (isSorted < 0 ? Math.max(0, l + isSorted) : isSorted);
} else {
i = _.sortedIndex(array, item);
return array[i] === item ? i : -1;
}
}
if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item, isSorted);
for (; i < l; i++) if (array[i] === item) return i;
return -1;
};
Another option would be to use Array.some (if available) in the following way:
Array.prototype.contains = function(obj) {
return this.some( function(e){ return e === obj } );
}
The anonymous function passed to Array.some will return true if and only if there is an element in the array that is identical to obj. Absent such an element, the function will not return true for any of the elements of the array, so Array.some will return false as well.
Wow, there are a lot of great answers to this question.
I didn't see one that takes a reduce approach so I'll add it in:
var searchForValue = 'pig';
var valueIsInArray = ['horse', 'cat', 'dog'].reduce(function(previous, current){
return previous || searchForValue === current ? true : false;
}, false);
console.log('The value "' + searchForValue + '" is in the array: ' + valueIsInArray);
Here's a fiddle of it in action.
The answer provided didn't work for me, but it gave me an idea:
Array.prototype.contains = function(obj)
{
return (this.join(',')).indexOf(obj) > -1;
}
It isn't perfect because items that are the same beyond the groupings could end up matching. Such as my example
var c=[];
var d=[];
function a()
{
var e = '1';
var f = '2';
c[0] = ['1','1'];
c[1] = ['2','2'];
c[2] = ['3','3'];
d[0] = [document.getElementById('g').value,document.getElementById('h').value];
document.getElementById('i').value = c.join(',');
document.getElementById('j').value = d.join(',');
document.getElementById('b').value = c.contains(d);
}
When I call this function with the 'g' and 'h' fields containing 1 and 2 respectively, it still finds it because the resulting string from the join is: 1,1,2,2,3,3
Since it is doubtful in my situation that I will come across this type of situation, I'm using this. I thought I would share incase someone else couldn't make the chosen answer work either.
Using array .map function that executes a function for every value in an array seems cleanest to me.
Ref: Array.prototype.map()
This method can work well both for simple arrays and for arrays of objects where you need to see if a key/value exists in an array of objects.
function inArray(myArray,myValue){
var inArray = false;
myArray.map(function(key){
if (key === myValue){
inArray=true;
}
});
return inArray;
};
var anArray = [2,4,6,8]
console.log(inArray(anArray, 8)); // returns true
console.log(inArray(anArray, 1)); // returns false
function inArrayOfObjects(myArray,myValue,objElement){
var inArray = false;
myArray.map(function(arrayObj){
if (arrayObj[objElement] === myValue) {
inArray=true;
}
});
return inArray;
};
var objArray = [{id:4,value:'foo'},{id:5,value:'bar'}]
console.log(inArrayOfObjects(objArray, 4, 'id')); // returns true
console.log(inArrayOfObjects(objArray, 'bar', 'value')); // returns true
console.log(inArrayOfObjects(objArray, 1, 'id')); // returns false
function setFound(){
var l = arr.length, textBox1 = document.getElementById("text1");
for(var i=0; i<l;i++)
{
if(arr[i]==searchele){
textBox1 .value = "Found";
return;
}
}
textBox1 .value = "Not Found";
return;
}
This program checks whether the given element is found or not. Id
text1 represents id of textbox and searchele represents element to be
searched (got fron user); if you want index, use i value
The simplest solution for a contains function, would be a function that looks like this :
var contains = function (haystack, needle) {
return !!~haystack.indexOf(needle);
}
Ideally, you wouldn't make this a stand-alone function, though, but part of a helper library :
var helper = {};
helper.array = {
contains : function (haystack, needle) {
return !!~haystack.indexOf(needle);
},
...
};
Now, if you happen to be one of those unlucky people who still needs to support IE<9 and thus can't rely on indexOf, you could use this polyfill, which I got from the MDN :
if (!Array.prototype.indexOf) {
Array.prototype.indexOf = function(searchElement, fromIndex) {
var k;
if (this == null) {
throw new TypeError('"this" is null or not defined');
}
var o = Object(this);
var len = o.length >>> 0;
if (len === 0) {
return -1;
}
var n = +fromIndex || 0;
if (Math.abs(n) === Infinity) {
n = 0;
}
if (n >= len) {
return -1;
}
k = Math.max(n >= 0 ? n : len - Math.abs(n), 0);
while (k < len) {
if (k in o && o[k] === searchElement) {
return k;
}
k++;
}
return -1;
};
}
I prefer simplicity:
var days = [1, 2, 3, 4, 5];
if ( 2 in days ) {console.log('weekday');}

Check value in array [duplicate]

This question already has answers here:
How do I check if an array includes a value in JavaScript?
(60 answers)
Closed 6 years ago.
I need to determine if a value exists in an array.
I am using the following function:
Array.prototype.contains = function(obj) {
var i = this.length;
while (i--) {
if (this[i] == obj) {
return true;
}
}
return false;
}
The above function always returns false.
The array values and the function call is as below:
arrValues = ["Sam","Great", "Sample", "High"]
alert(arrValues.contains("Sam"));
jQuery has a utility function for this:
$.inArray(value, array)
Returns index of value in array. Returns -1 if array does not contain value.
See also How do I check if an array includes an object in JavaScript?
var contains = function(needle) {
// Per spec, the way to identify NaN is that it is not equal to itself
var findNaN = needle !== needle;
var indexOf;
if(!findNaN && typeof Array.prototype.indexOf === 'function') {
indexOf = Array.prototype.indexOf;
} else {
indexOf = function(needle) {
var i = -1, index = -1;
for(i = 0; i < this.length; i++) {
var item = this[i];
if((findNaN && item !== item) || item === needle) {
index = i;
break;
}
}
return index;
};
}
return indexOf.call(this, needle) > -1;
};
You can use it like this:
var myArray = [0,1,2],
needle = 1,
index = contains.call(myArray, needle); // true
CodePen validation/usage
This is generally what the indexOf() method is for. You would say:
return arrValues.indexOf('Sam') > -1
Array.prototype.includes()
In ES2016, there is Array.prototype.includes().
The includes() method determines whether an array includes a certain element, returning true or false as appropriate.
Example
["Sam", "Great", "Sample", "High"].includes("Sam"); // true
Support
According to kangax and MDN, the following platforms are supported:
Chrome 47
Edge 14
Firefox 43
Opera 34
Safari 9
Node 6
Support can be expanded using Babel (using babel-polyfill) or core-js. MDN also provides a polyfill:
if (![].includes) {
Array.prototype.includes = function(searchElement /*, fromIndex*/ ) {
'use strict';
var O = Object(this);
var len = parseInt(O.length) || 0;
if (len === 0) {
return false;
}
var n = parseInt(arguments[1]) || 0;
var k;
if (n >= 0) {
k = n;
} else {
k = len + n;
if (k < 0) {k = 0;}
}
var currentElement;
while (k < len) {
currentElement = O[k];
if (searchElement === currentElement ||
(searchElement !== searchElement && currentElement !== currentElement)) {
return true;
}
k++;
}
return false;
};
}
It's almost always safer to use a library like lodash simply because of all the issues with cross-browser compatibilities and efficiency.
Efficiency because you can be guaranteed that at any given time, a hugely popular library like underscore will have the most efficient method of accomplishing a utility function like this.
_.includes([1, 2, 3], 3); // returns true
If you're concerned about the bulk that's being added to your application by including the whole library, know that you can include functionality separately:
var includes = require('lodash/collections/includes');
NOTICE: With older versions of lodash, this was _.contains() rather than _.includes().
Since ECMAScript6, one can use Set:
var myArray = ['A', 'B', 'C'];
var mySet = new Set(myArray);
var hasB = mySet.has('B'); // true
var hasZ = mySet.has('Z'); // false
tl;dr
function includes(k) {
for(var i=0; i < this.length; i++){
if( this[i] === k || ( this[i] !== this[i] && k !== k ) ){
return true;
}
}
return false;
}
Example
function includes(k) {
for(var i=0; i < this.length; i++){
if( this[i] === k || ( this[i] !== this[i] && k !== k ) ){
return true;
}
}
return false;
}
function log(msg){
$('#out').append('<div>' + msg + '</div>');
}
var arr = [1, "2", NaN, true];
arr.includes = includes;
log('var arr = [1, "2", NaN, true];');
log('<br/>');
log('arr.includes(1): ' + arr.includes(1));
log('arr.includes(2): ' + arr.includes(2));
log('arr.includes("2"): ' + arr.includes("2"));
log('arr.includes(NaN): ' + arr.includes(NaN));
log('arr.includes(true): ' + arr.includes(true));
log('arr.includes(false): ' + arr.includes(false));
#out{
font-family:monospace;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id=out></div>
Longer Answer
I know this question isn't really about whether or not to extend built-in objects, but the attempt of the OP and the comments on this answer highlight that debate. My comment from Feb 12, '13 cites an article that outlines this debate really well, however that link broke and I can't edit the original comment because too much time has passed, so I include it here.
If you're looking to extend the built-in Array object with a contains method, probably the best and most responsible way to do this would be to use this polyfill from MDN. (See also this section of the MDN article on Prototypical inheritance, which explains that "The only good reason for extending a built-in prototype is to backport the features of newer JavaScript engines; for example Array.forEach, etc.")
if (!Array.prototype.includes) {
Array.prototype.includes = function(searchElement /*, fromIndex*/ ) {
'use strict';
var O = Object(this);
var len = parseInt(O.length) || 0;
if (len === 0) {
return false;
}
var n = parseInt(arguments[1]) || 0;
var k;
if (n >= 0) {
k = n;
} else {
k = len + n;
if (k < 0) {k = 0;}
}
var currentElement;
while (k < len) {
currentElement = O[k];
if (searchElement === currentElement ||
(searchElement !== searchElement && currentElement !== currentElement)) {
return true;
}
k++;
}
return false;
};
}
Don't want strict equality, or want to choose?
function includes(k, strict) {
strict = strict !== false; // default is true
// strict = !!strict; // default is false
for(var i=0; i < this.length; i++){
if( (this[i] === k && strict) ||
(this[i] == k && !strict) ||
(this[i] !== this[i] && k !== k)
) {
return true;
}
}
return false;
}
My little contribution:
function isInArray(array, search)
{
return array.indexOf(search) >= 0;
}
//usage
if(isInArray(my_array, "my_value"))
{
//...
}
If you have access to ECMA 5 you can use the some method.
MDN SOME Method Link
arrValues = ["Sam","Great", "Sample", "High"];
function namePresent(name){
return name === this.toString();
}
// Note:
// namePresent requires .toString() method to coerce primitive value
// i.e. String {0: "S", 1: "a", 2: "m", length: 3, [[PrimitiveValue]]: "Sam"}
// into
// "Sam"
arrValues.some(namePresent, 'Sam');
=> true;
If you have access to ECMA 6 you can use the includes method.
MDN INCLUDES Method Link
arrValues = ["Sam","Great", "Sample", "High"];
arrValues.includes('Sam');
=> true;
Given the implementation of indexOf for IE (as described by eyelidlessness):
Array.prototype.contains = function(obj) {
return this.indexOf(obj) > -1;
};
You can use _.indexOf method or if you don't want to include whole Underscore.js library in your app, you can have a look how they did it and extract necessary code.
_.indexOf = function(array, item, isSorted) {
if (array == null) return -1;
var i = 0, l = array.length;
if (isSorted) {
if (typeof isSorted == 'number') {
i = (isSorted < 0 ? Math.max(0, l + isSorted) : isSorted);
} else {
i = _.sortedIndex(array, item);
return array[i] === item ? i : -1;
}
}
if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item, isSorted);
for (; i < l; i++) if (array[i] === item) return i;
return -1;
};
Another option would be to use Array.some (if available) in the following way:
Array.prototype.contains = function(obj) {
return this.some( function(e){ return e === obj } );
}
The anonymous function passed to Array.some will return true if and only if there is an element in the array that is identical to obj. Absent such an element, the function will not return true for any of the elements of the array, so Array.some will return false as well.
Wow, there are a lot of great answers to this question.
I didn't see one that takes a reduce approach so I'll add it in:
var searchForValue = 'pig';
var valueIsInArray = ['horse', 'cat', 'dog'].reduce(function(previous, current){
return previous || searchForValue === current ? true : false;
}, false);
console.log('The value "' + searchForValue + '" is in the array: ' + valueIsInArray);
Here's a fiddle of it in action.
The answer provided didn't work for me, but it gave me an idea:
Array.prototype.contains = function(obj)
{
return (this.join(',')).indexOf(obj) > -1;
}
It isn't perfect because items that are the same beyond the groupings could end up matching. Such as my example
var c=[];
var d=[];
function a()
{
var e = '1';
var f = '2';
c[0] = ['1','1'];
c[1] = ['2','2'];
c[2] = ['3','3'];
d[0] = [document.getElementById('g').value,document.getElementById('h').value];
document.getElementById('i').value = c.join(',');
document.getElementById('j').value = d.join(',');
document.getElementById('b').value = c.contains(d);
}
When I call this function with the 'g' and 'h' fields containing 1 and 2 respectively, it still finds it because the resulting string from the join is: 1,1,2,2,3,3
Since it is doubtful in my situation that I will come across this type of situation, I'm using this. I thought I would share incase someone else couldn't make the chosen answer work either.
Using array .map function that executes a function for every value in an array seems cleanest to me.
Ref: Array.prototype.map()
This method can work well both for simple arrays and for arrays of objects where you need to see if a key/value exists in an array of objects.
function inArray(myArray,myValue){
var inArray = false;
myArray.map(function(key){
if (key === myValue){
inArray=true;
}
});
return inArray;
};
var anArray = [2,4,6,8]
console.log(inArray(anArray, 8)); // returns true
console.log(inArray(anArray, 1)); // returns false
function inArrayOfObjects(myArray,myValue,objElement){
var inArray = false;
myArray.map(function(arrayObj){
if (arrayObj[objElement] === myValue) {
inArray=true;
}
});
return inArray;
};
var objArray = [{id:4,value:'foo'},{id:5,value:'bar'}]
console.log(inArrayOfObjects(objArray, 4, 'id')); // returns true
console.log(inArrayOfObjects(objArray, 'bar', 'value')); // returns true
console.log(inArrayOfObjects(objArray, 1, 'id')); // returns false
function setFound(){
var l = arr.length, textBox1 = document.getElementById("text1");
for(var i=0; i<l;i++)
{
if(arr[i]==searchele){
textBox1 .value = "Found";
return;
}
}
textBox1 .value = "Not Found";
return;
}
This program checks whether the given element is found or not. Id
text1 represents id of textbox and searchele represents element to be
searched (got fron user); if you want index, use i value
The simplest solution for a contains function, would be a function that looks like this :
var contains = function (haystack, needle) {
return !!~haystack.indexOf(needle);
}
Ideally, you wouldn't make this a stand-alone function, though, but part of a helper library :
var helper = {};
helper.array = {
contains : function (haystack, needle) {
return !!~haystack.indexOf(needle);
},
...
};
Now, if you happen to be one of those unlucky people who still needs to support IE<9 and thus can't rely on indexOf, you could use this polyfill, which I got from the MDN :
if (!Array.prototype.indexOf) {
Array.prototype.indexOf = function(searchElement, fromIndex) {
var k;
if (this == null) {
throw new TypeError('"this" is null or not defined');
}
var o = Object(this);
var len = o.length >>> 0;
if (len === 0) {
return -1;
}
var n = +fromIndex || 0;
if (Math.abs(n) === Infinity) {
n = 0;
}
if (n >= len) {
return -1;
}
k = Math.max(n >= 0 ? n : len - Math.abs(n), 0);
while (k < len) {
if (k in o && o[k] === searchElement) {
return k;
}
k++;
}
return -1;
};
}
I prefer simplicity:
var days = [1, 2, 3, 4, 5];
if ( 2 in days ) {console.log('weekday');}

removing value of imploded vars with javascript

i have this javascript var:
var mylist = '1,5,3,7,9,8,44,6';
I need to remove the 9, so that the final value is: 1,5,3,7,8,44,6
I usually do this server side with php (easy way). How can achieve this with javascript? A solution using jQuery would be even better.
considerations: it should work also if var is '99,9,96' or '9' or '99,9' or '9,98' ...etc.
my_list = my_list.split(',').filter(function(e) { return e != 9}).join(',');
Later edit: to support array.filter in IE:
//This prototype is provided by the Mozilla foundation and
//is distributed under the MIT license.
//http://www.ibiblio.org/pub/Linux/LICENSES/mit.license
if (!Array.prototype.filter)
{
Array.prototype.filter = function(fun)
{
var len = this.length;
if (typeof fun != "function")
throw new TypeError();
var res = new Array();
var thisp = arguments[1];
for (var i = 0; i < len; i++)
{
if (i in this)
{
var val = this[i]; // in case fun mutates this
if (fun.call(thisp, val, i, this))
res.push(val);
}
}
return res;
};
}
My suggestion:
var mylist = '1,5,3,7,9,8,44,6';
mylist = mylist.split(',').filter(function(elem, i) {
return elem !== '9';
}).join(',');
console.log(mylist); // = 1,5,3,7,8,44,6
Ref.: .filter()
filter():
Creates a new array with all elements
that pass the test implemented by the
provided function.

Determine whether an array contains a value [duplicate]

This question already has answers here:
How do I check if an array includes a value in JavaScript?
(60 answers)
Closed 6 years ago.
I need to determine if a value exists in an array.
I am using the following function:
Array.prototype.contains = function(obj) {
var i = this.length;
while (i--) {
if (this[i] == obj) {
return true;
}
}
return false;
}
The above function always returns false.
The array values and the function call is as below:
arrValues = ["Sam","Great", "Sample", "High"]
alert(arrValues.contains("Sam"));
jQuery has a utility function for this:
$.inArray(value, array)
Returns index of value in array. Returns -1 if array does not contain value.
See also How do I check if an array includes an object in JavaScript?
var contains = function(needle) {
// Per spec, the way to identify NaN is that it is not equal to itself
var findNaN = needle !== needle;
var indexOf;
if(!findNaN && typeof Array.prototype.indexOf === 'function') {
indexOf = Array.prototype.indexOf;
} else {
indexOf = function(needle) {
var i = -1, index = -1;
for(i = 0; i < this.length; i++) {
var item = this[i];
if((findNaN && item !== item) || item === needle) {
index = i;
break;
}
}
return index;
};
}
return indexOf.call(this, needle) > -1;
};
You can use it like this:
var myArray = [0,1,2],
needle = 1,
index = contains.call(myArray, needle); // true
CodePen validation/usage
This is generally what the indexOf() method is for. You would say:
return arrValues.indexOf('Sam') > -1
Array.prototype.includes()
In ES2016, there is Array.prototype.includes().
The includes() method determines whether an array includes a certain element, returning true or false as appropriate.
Example
["Sam", "Great", "Sample", "High"].includes("Sam"); // true
Support
According to kangax and MDN, the following platforms are supported:
Chrome 47
Edge 14
Firefox 43
Opera 34
Safari 9
Node 6
Support can be expanded using Babel (using babel-polyfill) or core-js. MDN also provides a polyfill:
if (![].includes) {
Array.prototype.includes = function(searchElement /*, fromIndex*/ ) {
'use strict';
var O = Object(this);
var len = parseInt(O.length) || 0;
if (len === 0) {
return false;
}
var n = parseInt(arguments[1]) || 0;
var k;
if (n >= 0) {
k = n;
} else {
k = len + n;
if (k < 0) {k = 0;}
}
var currentElement;
while (k < len) {
currentElement = O[k];
if (searchElement === currentElement ||
(searchElement !== searchElement && currentElement !== currentElement)) {
return true;
}
k++;
}
return false;
};
}
It's almost always safer to use a library like lodash simply because of all the issues with cross-browser compatibilities and efficiency.
Efficiency because you can be guaranteed that at any given time, a hugely popular library like underscore will have the most efficient method of accomplishing a utility function like this.
_.includes([1, 2, 3], 3); // returns true
If you're concerned about the bulk that's being added to your application by including the whole library, know that you can include functionality separately:
var includes = require('lodash/collections/includes');
NOTICE: With older versions of lodash, this was _.contains() rather than _.includes().
Since ECMAScript6, one can use Set:
var myArray = ['A', 'B', 'C'];
var mySet = new Set(myArray);
var hasB = mySet.has('B'); // true
var hasZ = mySet.has('Z'); // false
tl;dr
function includes(k) {
for(var i=0; i < this.length; i++){
if( this[i] === k || ( this[i] !== this[i] && k !== k ) ){
return true;
}
}
return false;
}
Example
function includes(k) {
for(var i=0; i < this.length; i++){
if( this[i] === k || ( this[i] !== this[i] && k !== k ) ){
return true;
}
}
return false;
}
function log(msg){
$('#out').append('<div>' + msg + '</div>');
}
var arr = [1, "2", NaN, true];
arr.includes = includes;
log('var arr = [1, "2", NaN, true];');
log('<br/>');
log('arr.includes(1): ' + arr.includes(1));
log('arr.includes(2): ' + arr.includes(2));
log('arr.includes("2"): ' + arr.includes("2"));
log('arr.includes(NaN): ' + arr.includes(NaN));
log('arr.includes(true): ' + arr.includes(true));
log('arr.includes(false): ' + arr.includes(false));
#out{
font-family:monospace;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id=out></div>
Longer Answer
I know this question isn't really about whether or not to extend built-in objects, but the attempt of the OP and the comments on this answer highlight that debate. My comment from Feb 12, '13 cites an article that outlines this debate really well, however that link broke and I can't edit the original comment because too much time has passed, so I include it here.
If you're looking to extend the built-in Array object with a contains method, probably the best and most responsible way to do this would be to use this polyfill from MDN. (See also this section of the MDN article on Prototypical inheritance, which explains that "The only good reason for extending a built-in prototype is to backport the features of newer JavaScript engines; for example Array.forEach, etc.")
if (!Array.prototype.includes) {
Array.prototype.includes = function(searchElement /*, fromIndex*/ ) {
'use strict';
var O = Object(this);
var len = parseInt(O.length) || 0;
if (len === 0) {
return false;
}
var n = parseInt(arguments[1]) || 0;
var k;
if (n >= 0) {
k = n;
} else {
k = len + n;
if (k < 0) {k = 0;}
}
var currentElement;
while (k < len) {
currentElement = O[k];
if (searchElement === currentElement ||
(searchElement !== searchElement && currentElement !== currentElement)) {
return true;
}
k++;
}
return false;
};
}
Don't want strict equality, or want to choose?
function includes(k, strict) {
strict = strict !== false; // default is true
// strict = !!strict; // default is false
for(var i=0; i < this.length; i++){
if( (this[i] === k && strict) ||
(this[i] == k && !strict) ||
(this[i] !== this[i] && k !== k)
) {
return true;
}
}
return false;
}
My little contribution:
function isInArray(array, search)
{
return array.indexOf(search) >= 0;
}
//usage
if(isInArray(my_array, "my_value"))
{
//...
}
If you have access to ECMA 5 you can use the some method.
MDN SOME Method Link
arrValues = ["Sam","Great", "Sample", "High"];
function namePresent(name){
return name === this.toString();
}
// Note:
// namePresent requires .toString() method to coerce primitive value
// i.e. String {0: "S", 1: "a", 2: "m", length: 3, [[PrimitiveValue]]: "Sam"}
// into
// "Sam"
arrValues.some(namePresent, 'Sam');
=> true;
If you have access to ECMA 6 you can use the includes method.
MDN INCLUDES Method Link
arrValues = ["Sam","Great", "Sample", "High"];
arrValues.includes('Sam');
=> true;
Given the implementation of indexOf for IE (as described by eyelidlessness):
Array.prototype.contains = function(obj) {
return this.indexOf(obj) > -1;
};
You can use _.indexOf method or if you don't want to include whole Underscore.js library in your app, you can have a look how they did it and extract necessary code.
_.indexOf = function(array, item, isSorted) {
if (array == null) return -1;
var i = 0, l = array.length;
if (isSorted) {
if (typeof isSorted == 'number') {
i = (isSorted < 0 ? Math.max(0, l + isSorted) : isSorted);
} else {
i = _.sortedIndex(array, item);
return array[i] === item ? i : -1;
}
}
if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item, isSorted);
for (; i < l; i++) if (array[i] === item) return i;
return -1;
};
Another option would be to use Array.some (if available) in the following way:
Array.prototype.contains = function(obj) {
return this.some( function(e){ return e === obj } );
}
The anonymous function passed to Array.some will return true if and only if there is an element in the array that is identical to obj. Absent such an element, the function will not return true for any of the elements of the array, so Array.some will return false as well.
Wow, there are a lot of great answers to this question.
I didn't see one that takes a reduce approach so I'll add it in:
var searchForValue = 'pig';
var valueIsInArray = ['horse', 'cat', 'dog'].reduce(function(previous, current){
return previous || searchForValue === current ? true : false;
}, false);
console.log('The value "' + searchForValue + '" is in the array: ' + valueIsInArray);
Here's a fiddle of it in action.
The answer provided didn't work for me, but it gave me an idea:
Array.prototype.contains = function(obj)
{
return (this.join(',')).indexOf(obj) > -1;
}
It isn't perfect because items that are the same beyond the groupings could end up matching. Such as my example
var c=[];
var d=[];
function a()
{
var e = '1';
var f = '2';
c[0] = ['1','1'];
c[1] = ['2','2'];
c[2] = ['3','3'];
d[0] = [document.getElementById('g').value,document.getElementById('h').value];
document.getElementById('i').value = c.join(',');
document.getElementById('j').value = d.join(',');
document.getElementById('b').value = c.contains(d);
}
When I call this function with the 'g' and 'h' fields containing 1 and 2 respectively, it still finds it because the resulting string from the join is: 1,1,2,2,3,3
Since it is doubtful in my situation that I will come across this type of situation, I'm using this. I thought I would share incase someone else couldn't make the chosen answer work either.
Using array .map function that executes a function for every value in an array seems cleanest to me.
Ref: Array.prototype.map()
This method can work well both for simple arrays and for arrays of objects where you need to see if a key/value exists in an array of objects.
function inArray(myArray,myValue){
var inArray = false;
myArray.map(function(key){
if (key === myValue){
inArray=true;
}
});
return inArray;
};
var anArray = [2,4,6,8]
console.log(inArray(anArray, 8)); // returns true
console.log(inArray(anArray, 1)); // returns false
function inArrayOfObjects(myArray,myValue,objElement){
var inArray = false;
myArray.map(function(arrayObj){
if (arrayObj[objElement] === myValue) {
inArray=true;
}
});
return inArray;
};
var objArray = [{id:4,value:'foo'},{id:5,value:'bar'}]
console.log(inArrayOfObjects(objArray, 4, 'id')); // returns true
console.log(inArrayOfObjects(objArray, 'bar', 'value')); // returns true
console.log(inArrayOfObjects(objArray, 1, 'id')); // returns false
function setFound(){
var l = arr.length, textBox1 = document.getElementById("text1");
for(var i=0; i<l;i++)
{
if(arr[i]==searchele){
textBox1 .value = "Found";
return;
}
}
textBox1 .value = "Not Found";
return;
}
This program checks whether the given element is found or not. Id
text1 represents id of textbox and searchele represents element to be
searched (got fron user); if you want index, use i value
The simplest solution for a contains function, would be a function that looks like this :
var contains = function (haystack, needle) {
return !!~haystack.indexOf(needle);
}
Ideally, you wouldn't make this a stand-alone function, though, but part of a helper library :
var helper = {};
helper.array = {
contains : function (haystack, needle) {
return !!~haystack.indexOf(needle);
},
...
};
Now, if you happen to be one of those unlucky people who still needs to support IE<9 and thus can't rely on indexOf, you could use this polyfill, which I got from the MDN :
if (!Array.prototype.indexOf) {
Array.prototype.indexOf = function(searchElement, fromIndex) {
var k;
if (this == null) {
throw new TypeError('"this" is null or not defined');
}
var o = Object(this);
var len = o.length >>> 0;
if (len === 0) {
return -1;
}
var n = +fromIndex || 0;
if (Math.abs(n) === Infinity) {
n = 0;
}
if (n >= len) {
return -1;
}
k = Math.max(n >= 0 ? n : len - Math.abs(n), 0);
while (k < len) {
if (k in o && o[k] === searchElement) {
return k;
}
k++;
}
return -1;
};
}
I prefer simplicity:
var days = [1, 2, 3, 4, 5];
if ( 2 in days ) {console.log('weekday');}

Categories