Need to find whether array object If exist in array. I have one arrayObject and array collections.
my code:
var array = [
{
id:0,
item_fields:{text: "stack", type: "2", options: null},
item_id:"540551c1-1744-4f09-920f-75350ba23cb6",
item_parent:"e50b00d5-8c3e-449e-92ba-41ff9d46babe",
sequence:-1
},
{
id:0,
item_field_type:"multiChoiceNumeric",
item_fields:{text: "overflow", type: "RangeNumeric", options: null},
item_id:"1bacc69f-d8c9-4107-af60-295f8994d249",
item_parent:"e50b00d5-8c3e-449e-92ba-41ff9d46babe",
sequence:-1
}];
var arrObj =
{
id:0,
item_field_type:"multiChoiceNumeric",
item_fields:{text: "stack", type: "2", options: null},
item_id:"540551c1",
item_parent:"e50b00d5",
sequence:-1
}
This query returns false:
array.some(function(element){return element == arrObj})
This query returns -1 (If not found):
jQuery.inArray(arrObj,array)
Why do both queries return not found results? What should I do to get a correct result?
In JavaScript, variable assignment to Object is similar to a pointer in C; the variable is a reference to the memory location of the Object, not the Object and its contents itself.
var x = {};
var y = {};
x === y;
// false
Rather than compare equality of references to objects, you can update the callback in array.some() to check for deep equality, but this can get cumbersome.
It may be better to compare a key in the objects that you know will be unique, such as "item_id":
array.some(function(element) {
return element.item_id === arrObj.item_id;
});
Related
My usage will contain 6 different object types (some which contain double nested arrays), and any possibility of number of entries, on the condition that an given entry is unique.
These objects do not have a consistent unique identifier (a unique identifier is applied in backend on submission).
here is an example of what the array may look like (only 2 object types):
arr = [
{name:"aaa",time:15},
{name:"aaa",time:22},
{timeline: "250", chars[{a},{b},{c}]},
{timeline: "220", chars[{d},{e},{f}]},
]
obj = {name:"aaa",time:22}
My intention is to gain a true or false based on if obj is inside arr
I have tried methods:
I was suggested this method & it errors: #<Object> is not a function
console.log(arr.find(obj))
I also found this suggestion but it will always return false even with the element present
console.log(arr.includes(object))
I tried this method myself, though it will always fail.
console.log(arr.filter((element, index) => element === obj)
With attempt 4, If I was to compare name, this would be insufficient as unique time would be ignored missing valid entries.
If I was to pass every field, this would also not work as each object may or may not have the field and cause error.
Its not really possible to manually pre-filter filter into distinct categories, as every time a new type is added it will need manually adding to the filter.
If there is a library which could do this that you know of, please let me know as that would be perfect. Otherwise any other suggestions (excluding separating arrays) Would be greatly appreciated.
Use arr.some() to check if the required object is present in the array.
To compare the objects, a simpler way is to Stringify both the Objects and compare them.
const arr = [
{name:"aaa",time:15},
{name:"aaa",time:22},
{name: "aaa", chars: ["a", "b", "c"]},
{name: "bbb", chars: ["d", "e", "f"]},
]
const obj1 = {name:"aaa", time: 15}
const obj2 = {name:"aaa",chars: ["a", "b", "c"]}
console.log(arr.some((element) => JSON.stringify(element) === JSON.stringify(obj1))) // true
console.log(arr.some((element) => JSON.stringify(element) === JSON.stringify(obj2))) // true
Didn't give much thought on performance.
I didn't put much thought on performace here but this might help:
function checkObjectInArray(arr, obj) {
const res = arr.some((el) => deepEqual(el, obj));
console.log(res);
}
function deepEqual(obj1, obj2) {
if (Object.keys(obj1).length !== Object.keys(obj2).length) return false;
for (let prop in obj1) {
if (!obj2.hasOwnProperty(prop) || obj2[prop] !== obj1[prop]) {
return false;
}
}
return true;
}
in your case you can use it like:
arr = [
{ name: "aaa", time: 15 },
{ name: "aaa", time: 22 },
{ timeline: "250", data: ["2", "3", "4"] },
{ timeline: "251", data: ["2", "3", "4"] }, // what is chars[{d},{e},{f}] ?!
];
obj = { name: "aaa", time: 22 };
checkObjectInArray(arr, obj);
Observation : arr is not a valid array. Nested chars is not containing a valid value.
Solution : You can simply achieve the requirement by Just converting the JSON object into a JSON string and by comparing.
This solution works fine as you are just trying to find a single object in the passed arr.
Live Demo :
const arr = [
{name:"aaa",time:15},
{name:"aaa",time:22},
{timeline: "250", chars: [{a: 1},{b: 2},{c: 3}]},
{timeline: "220", chars: [{d: 4},{e: 5},{f: 6}]},
];
const obj = {name:"aaa",time:22};
const res = JSON.stringify(arr).indexOf(JSON.stringify(obj)) !== -1 ? true : false;
console.log(res);
The objects are pulled from the backend, the objects can be different lengths and can contain different values.
I want to custom sort these objects in this order of the array below:
let array = ["packhouse", "location", "date", "time"]
this is what I can do (searching through the web):
var myArray = [{
name: 'packhouse'
},
{
name: 'notPackhouse',
date: "date"
},
{
name: 'a'
},
];
myArray.sort(function(a, b) {
return array.indexOf(a.name) - sortOrder.indexOf(b.name);
});
the data being pulled doesnt always have "packhouse" or could be a bigger length than the custom order array. is there a better solution for this?
I have an array of JSON-like object[Object,Object...] (I was calling it array of JSON object until I see this ) and I would like to go through each item in it. The JSON object has 3 values {name:"name",date:"2015-01-01",c:3} in it and I want to put each of them into a new array. Should I use a for item in JSONArary{item = ...} or for (i=0,i<len,i++){array[i] = ....} or should I JSONArray.pop()? Which one is faster and why? What if I want to reverse the array? Do reversing cost a lot?
for (i=0,i<len,i++){array[i] = ....} should be faster than for item in JSONArary{item = ...} because the later will traverse all enumerable properties on this object, while some of these properties are unnecessary.
When you want to iterate over just the indexed properties of an array, the only guaranteed way to keep things semantically consistent is to use an integer index.
For your reference: Why is using "for...in" with array iteration a bad idea?
Even Google make the JavaScript coding style guide as:
for-in loop: Only for iterating over keys in an object/map/hash
I have a faster way, use $.map:
var oldArray = [{
name: "name1",
date: "2015-01-01",
c: 3
}, {
name: "name2",
date: "2015-01-01",
c: 3
}, {
name: "name3",
date: "2015-01-01",
c: 3
}];
var newArray = $.map(oldArray, function (item) {
return {
FullName: item.name,
RegisterDate: item.date
};
});
alert(JSON.stringify(newArray));
Hope this help.
I have a javascript dictionary:
{
"a": {
"b": {
"c": null,
"d": null
}
}
}
How can I turn it into a JSON object which I can specify the name and children property? Is there any elegant way to do it?
The JSON object could be:
{
name:"a"
children: [{
name:"b",
children: [{
name:"c",
children: null
},{
name:"d",
children: null}]
}]
}
You could create a recursive function for generating your output:
var x = {
"a": {
"b": {
"c": null,
"d": null
}
}
};
function generate(item, key) {
var result = {
name: key,
children: []
};
for (var _ in item)
result.children.push(generate(item[_], _))
if (result.children.length == 0)
result.children = null;
return (key == undefined) ? result.children : result;
}
console.log(JSON.stringify(generate(x), null, 1));
Output:
[
{
"name": "a",
"children": [
{
"name": "b",
"children": [
{
"name": "c",
"children": null
},
{
"name": "d",
"children": null
}
]
}
]
}
]
The above generate function returns a list instead of a dictionary, because it's possible to have more than one name at the root level. But if we are sure that we have only one name at the root name, we can generate the json like this:
console.log(JSON.stringify(generate(x)[0], null, 1));
Here's my solution. It's similar to JuniorCompressor's.
function generate(obj) {
// Return primitives as-is
if (!(obj instanceof Object)) return obj;
// Loop through object properties and generate array
var result = [];
for (var key in obj) {
result.push({
name: key,
children: generate(obj[key])
});
}
// Return resulting array
return result;
}
As mentioned, the resulting object will actually be an array (in case there is more than one root-level property in the original object). If you really need the resulting object to be an object with only properties name and value, then you should access the first element of the resulting array, like this:
generate(obj)[0]
Solution
You need a recursive function, which calls itself for children. Note that in your example, there is only one top-level child (a). I instead use the assumption that the top-level 'name' refers to the name of the actual object itself. If you want to get results exactly like you demonstrate, from an object called 'obj', run toJSON(obj).children[0]. For the overall function, try something like the following:
function toJSON(obj, name) {
var subTree = {
name: name,
children: []
};
if (obj !== null && Object.keys(obj).length >= 1) {
for (var child in obj) {
subTree.children.push(toJSON(obj[child], child));
}
} else {
subTree.children = null;
}
return subTree;
}
Results of toJSON(obj).children[0]:
{
"name": "a",
"children": [{
"name": "b",
"children": [{
"name": "c",
"children": null
},{
"name": "d",
"children": null
}]
}]
}
Results of toJSON(obj, 'obj'):
{
"name": "obj",
"children": [{
"name": "a",
"children": [{
"name": "b",
"children": [{
"name": "c",
"children":null
},
{
"name": "d",
"children": null
}]
}]
}]
}
Here's a line-by-line explanation:
Declares the function, which expects two arguments: the object, and it's name. If you're going to be using toJSON(obj).children[0], though, don't bother with the second argument. It won't affect the result.
Declares the result, an object containing information about the current level and all levels below in the object. If you consider the object a tree, this result contains information about the current branch, and all it's branches.
Declares the property 'name', containing the name/key of the object at the current level. When you call the function, you need to include the name as second argument because there is no way of dynamically finding the name of a variable. They're passed into functions by value. As described above, though, if you're looking for results EXACTLY like those in your example, you're going to use toJSON(obj).children[0], instead of toJSON(obj, 'obj'), and then don't need to bother with the second argument.
Declares the children array, to be filled below
Terminates the declaration begun on Line 2
Checks if the object ISN'T null, and that it has children, using a handy method of the Object built-in object, running Lines 7, 8 and 9 if so
Iterates over the children of the object, running Line 8 for each child
Recursively runs the toJSON() function for each child, to get it's subTree. Because the children can't dynamically figure out their own names, it passes those in as well.
Terminates the for loop begun at Line 7
If there are no children, run Line 11. This is only run if Lines 7, 8 and 9 are not.
Sets children to null (only run if there are no children, as checked by Line 6)
Terminates the else started at line 10
Returns the current subTree, either to the function if called recursively by the function, or to you if you called it yourself
Terminates the function
Information about the Previous Version, Pre-edit
The original function only used one argument, whereas that above has another argument for 'name'. This is because the original tried to figure out the name of each level within that same level, which I have since realized isn't possible in Javascript. Basically, the original didn't work, and an extra argument had to be added to make it work. For records' sake, though, here was the original function:
// THIS FUNCTION DOESN'T WORK. IT'S HERE ONLY FOR HISTORICAL ACCURACY:
function toJSON(obj) {
var subTree = {
name: obj.constructor.name, // This should get the object key
children: []
};
if (Object.keys(obj).length >= 1) { // If there is at least one child
for (var child in obj) {
subTree.children.push(toJSON(obj[child]));
}
} else {
subTree.children = null;
}
return subTree;
}
I need to merge two objects in a code path that is going to be heavily used. The code works, but I am concerned it is not optimized enough for speed and I am looking for any suggestions to improve/replace what I have come up with. I originally started working off an example at the end of this issue: How can I merge properties of two JavaScript objects dynamically?. That solution works well for simple objects. However, my needs have a twist to it which is where the performance concerns come in. I need to be able to support arrays such that
an array of simple values will look for values in the new object and add those to the end of the existing object and
an array of objects will either merge objects (based off existence of an id property) or push new objects (objects whose id property does not exist) to the end of the existing array.
I do not need functions/method cloning and I don't care about hasOwnProperty since the objects go back to JSON strings after merging.
Any suggestions to help me pull every last once of performance from this would be greatly appreciated.
var utils = require("util");
function mergeObjs(def, obj) {
if (typeof obj == 'undefined') {
return def;
} else if (typeof def == 'undefined') {
return obj;
}
for (var i in obj) {
// if its an object
if (obj[i] != null && obj[i].constructor == Object)
{
def[i] = mergeObjs(def[i], obj[i]);
}
// if its an array, simple values need to be joined. Object values need to be remerged.
else if(obj[i] != null && utils.isArray(obj[i]) && obj[i].length > 0)
{
// test to see if the first element is an object or not so we know the type of array we're dealing with.
if(obj[i][0].constructor == Object)
{
var newobjs = [];
// create an index of all the existing object IDs for quick access. There is no way to know how many items will be in the arrays.
var objids = {}
for(var x= 0, l= def[i].length ; x < l; x++ )
{
objids[def[i][x].id] = x;
}
// now walk through the objects in the new array
// if the ID exists, then merge the objects.
// if the ID does not exist, push to the end of the def array
for(var x= 0, l= obj[i].length; x < l; x++)
{
var newobj = obj[i][x];
if(objids[newobj.id] !== undefined)
{
def[i][x] = mergeObjs(def[i][x],newobj);
}
else {
newobjs.push(newobj);
}
}
for(var x= 0, l = newobjs.length; x<l; x++) {
def[i].push(newobjs[x]);
}
}
else {
for(var x=0; x < obj[i].length; x++)
{
var idxObj = obj[i][x];
if(def[i].indexOf(idxObj) === -1) {
def[i].push(idxObj);
}
}
}
}
else
{
def[i] = obj[i];
}
}
return def;}
The object samples to merge:
var obj1 = {
"name" : "myname",
"status" : 0,
"profile": { "sex":"m", "isactive" : true},
"strarr":["one", "three"],
"objarray": [
{
"id": 1,
"email": "a1#me.com",
"isactive":true
},
{
"id": 2,
"email": "a2#me.com",
"isactive":false
}
]
};
var obj2 = {
"name" : "myname",
"status" : 1,
"newfield": 1,
"profile": { "isactive" : false, "city": "new York"},
"strarr":["two"],
"objarray": [
{
"id": 1,
"isactive":false
},
{
"id": 2,
"email": "a2modified#me.com"
},
{
"id": 3,
"email": "a3new#me.com",
"isactive" : true
}
]
};
Once merged, this console.log(mergeObjs(obj1, obj2)) should produce this:
{ name: 'myname',
status: 1,
profile: { sex: 'm', isactive: false, city: 'new York' },
strarr: [ 'one', 'three', 'two' ],
objarray:
[ { id: 1, email: 'a1#me.com', isactive: false },
{ id: 2, email: 'a2modified#me.com', isactive: false },
{ id: 3, email: 'a3new#me.com', isactive: true } ],
newfield: 1 }
I'd check out: https://github.com/bestiejs/lodash
_.merge is not on the list of 'optimized' functions, but this is a battle tested, battle hardened. He also has a performance suite, could ask how you might contribute to the perf suite to get some visibility into the merge implementation.
https://github.com/bestiejs/lodash/blob/master/lodash.js#L1677-1738
Edit: As an aside, I wouldn't prematurely optimize. I would see if this is actually a problem in your use case and then move on to actual data. I would look at something like: https://github.com/felixge/faster-than-c
Basic tenets:
Collect data
Analyze it
Find problems
Fix them
Repeat
He's got tips on each of those.
If you don't use Lo-Dash, and just want a tool to merge two objects including their arrays, use deepmerge: https://github.com/nrf110/deepmerge
npm install deepmerge