Pairing multiple javascript arrays - javascript

I'm trying to solve a problem I have with multiple javascript arrays.
So basically the result I want is to match the arrays of a dropdown box with other values from other arrays that I will display.
The arrays contain different values, but the order is the most important thing
var array1 = [2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22];
var array2 = [30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50];
var array3 = [36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56];
Let's say the user selects number 4, then I need to somehow select 32 in array2 and 38 in array3.
Any suggestions are gladly accepted, Thanks!

Get the index from the first array, with Array.prototype.indexOf
var index = array1.indexOf(4);
Get the values from other arrays with that index, like this
console.log(array2[index], array3[index]);
Note: If the value being searched is not found in the array, indexOf will not fail with an error but it will simply return -1. So, you might want to check before using that to access the elements from other arrays, like this
var index = array1.indexOf(4);
if (index !== -1) {
console.log(array2[index], array3[index]);
} else {
console.log("Invalid element selected");
}

Any time you have multiple parallel arrays, you should really consider refactoring it into a single array of objects. That way you never have to worry about keeping them synched. For example:
var myArray = [ { val1: 2, val2: 30, val3: 36 }, { val1: 4, val2: 32, val3: 38 }, ...];
Now to find the value for 4 you can simply do something like (although a simple for loop might be more efficient since you know there is only ever one result):
var myValues = myArray.filter(function(item) { return item.val1 === 4 });
And then access myValues[0].val2 and myValues[0].val3.
Or, if you are always looking up by the first value, you can use that as your key for an object that maps to your other two values. Something like:
var myArray = { 2: { val2: 30, val3: 36 }, 4: { val2: 32, val3: 38 },...};
Now if you want the other two values for 4 you can simply:
var value2 = myArray[4];
var value3 = myArray[4];

Assuming those are not only arrays and values, but you have actual <select> dropdown boxes:
Accessing the selected value is not only possible by using select1.value, but also by using select1.options[select1.selectedIndex].value. That.selectedIndex is what we are interested in, and you can use that equivalently on the option collections of the other two dropdowns, or the arrays with their values:
select2.options[select1.selectedIndex].value
array2[select1.selectedIndex]
select3.options[select1.selectedIndex].value
array3[select1.selectedIndex]
If you access them via the options collection you will need to make sure that one option is actually selected (select1.selectedIndex != -1), otherwise you'd get an exception.

Do it like this,
var valueFromSelect = 4;
var array1 = [2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22];
var array2 = [30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50];
var array3 = [36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56];
for(var i = 0; i < array1.length; i++){
if(valueFromSelect == array1[i]){
console.log(array2[i], array3[i]);
break;
}
}
I suggest you don't use indexOf, it's not compatible with IE < 9 read more about that here indexOf MDN

Related

How can I get the largest number value along with the username from this array?

Im trying to get the user & value with the highest number from this array but have had no luck in my searches. I'm starting to wonder if my array is poorly written.
{
"radtech2": 1,
"conorlarkin4": 25,
"jdon2001": 15,
"nobel_veo": 101,
"frapoden": 1,
"duckyboy17": 31,
"faeded": 30,
"jimbob20001": 17,
"leb0wski": 15,
"3cavalry": 2,
"hardoak22": 25,
"deep_slide": 10000,
"sillywil": 7
}
const users = {
"radtech2": 1,
"conorlarkin4": 25,
"jdon2001": 15,
"nobel_veo": 101,
"frapoden": 1,
"duckyboy17": 31,
"faeded": 30,
"jimbob20001": 17,
"leb0wski": 15,
"3cavalry": 2,
"hardoak22": 25,
"deep_slide": 10000,
"sillywil": 7
};
const highestUser = users => Object.keys(users).reduce(
(highest, current) => highest.val > users[current] ? highest : { user: current, val: users[current] },
{ user: undefined, val: -Infinity }
).user;
console.log(highestUser(users));
Use keys() and entries() methods to search your JSON object. Save largest value into e.g. const largest and then find out which key belongs to this value.
Let me try to squeeze it into a one-liner approach using Object.keys() and Array.reduce().
const users = {
"radtech2": 1,
"conorlarkin4": 25,
"jdon2001": 15,
"nobel_veo": 101,
"frapoden": 1,
"duckyboy17": 31,
"faeded": 30,
"jimbob20001": 17,
"leb0wski": 15,
"3cavalry": 2,
"hardoak22": 25,
"deep_slide": 10000,
"sillywil": 7
};
const res = Object.keys(users).reduce((a, b) => users[a] > users[b] ? a : b);
console.log(res);
How the above code works is that I get the array of keys from the users object, and I use reduce to get the highest possible value and return the corresponding property from the array obtained from Object.keys().
What you show in your question is an Object, not an Array; however, it does need to be turned into an array in order to work with it.
You can do that with Object.entries(), which will return an array of all the key/value pairs in the object.
Then you can use Array.reduce() to extract the one with the largest value.
const data = {
"radtech2": 1,
"conorlarkin4": 25,
"jdon2001": 15,
"nobel_veo": 101,
"frapoden": 1,
"duckyboy17": 31,
"faeded": 30,
"jimbob20001": 17,
"leb0wski": 15,
"3cavalry": 2,
"hardoak22": 25,
"deep_slide": 10000,
"sillywil": 7
}
let winner = Object.entries(data).reduce((a, b) => (a[1] > b[1]) ? a : b)
console.log(winner)

Extract data from an array of Object

I have this array of Object that I am getting from my database:
[Array of Object][1]
I would like to make an array of array for each value, but I can't manage to find a way to do it as I'm a beginner of javascript.
For example :
var Stats=[
[39,49,43,42,41,35], //SGW Value for each Object
[37,44,49,46,52,42], //UD Value for each Object
[8,11,8,8,16,15], //Virtual Value for each Object
...
]
The goal is to make a chart on chart.js that look like that :
[Chart Goal][2]
I would need to loop the dataset because I'll add more data and it would be way too long to set each dataset individually.
Thanks for your time.
You can do it like this:
let array1 = [
{
param1: 10,
param2: 20
},
{
param1: 30,
param2: 40
}
]
let array2 = array1.map(item => Object.values(item));
console.log(array2); // prints [[10, 20], [30, 40]]
First of all you need to create an array for each property you want to plot; i.e.:
var fsp = [],
msg = [],
sgw = [];
Then you can loop over your dataset and put the data in each array:
yourArray.forEach(function(obj){
//obj takes the value of each object in the database
fsp.push(obj.fsp);
msg.push(obj.msg);
sgw.push(obj.sgw);
})
or, if you are more familiar with for loop
for(var obj of yourArray){
fsp.push(obj.fsp);
msg.push(obj.msg);
sgw.push(obj.sgw);
}
Finally you can create an array as you pointed in your example
var result = [];
result.push(fsp, msg, sgw);
And the result will be
[
[89, 59, 43, 60, 81, 34, 28, 58, 75, 41],
[77, 91, 4, 56, 6, 1, 42, 82, 97, 18],
[24, 34, 4, 13, 75, 34, 14, 41, 20, 38]
]
For more informations take a look at Array.forEach(), Array.push() and for...of documentations
EDIT
As you pointed in your comment, you can generate arrays dynamically creating an object like var arrays = {};. Then in forEach(), or if for...of, you need to loop over objects with a for...in loop. The variable you declare in loop's head takes the value of index, numeric for Arrays, literal for Objects. You have to do something like:
yourArray.forEach(function(obj){
for(let index in obj){
if(!arrays[index]) // check if property has already been set and initialized
arrays[index] = []; // if not, it's initialized
arrays[index].push(obj[index]) // push the value into the array
}
})
Note that Object has been treated as Array because you access its properties with a variable filled at runtime.
The result will be:
arrays = {
fsp: [89, 59, 43, 60, 81, 34, 28, 58, 75, 41],
msg: [77, 91, 4, 56, 6, 1, 42, 82, 97, 18],
sgw: [24, 34, 4, 13, 75, 34, 14, 41, 20, 38]
}
To obtain only arrays use Object.values().
If you cannot imagine how this works, I suggest you to make some examples in Chrome Developer Tools' console, or in Node's console, or wherever you can have a realtime feedback, putting in the middle of code some console.log() of variables

Trouble at comparing arrays

I have 'shared.checkedFacility' scope array in controller which read something like:
[14, 49, 93, 122, 44, 40, 88, 83, 65, 9, 38, 28, 8, 53, 125, 155]
and i am dynamically generating two dimensional array in front end where, for example, single dimentional array from 'shared.facilities[$parent.$index]' read like
{"0":56,"1":13,"2":49,"3":3,"4":11,"5":7,"6":19,"7":4,"8":9,"9":131,"10":21}
Now i am comparing this two array in ng-show argument like
containsAny(shared.checkedFacility,shared.facilities[$index])
Where as function defination is like
function containsAny(source, target) {
console.log("contains called");
var result = source.filter(function(item) {
return target.indexOf(item) > -1
});
return (result.length > 0);
}
But some how this function is not returning true or false, how to make it work?
Please rescue me since i am afresh here in Angular or in Javascript Env straight from PHP.
You can use Object.keys(), .map() to create an array from shared.facilities[$parent.$index]
// `shared.checkedFacility`
var checkedFacility = [14
, 49
, 93
, 122
, 44
, 40
, 88
, 83
, 65
, 9
, 38
, 28
, 8
, 53
, 125
, 155
];
// shared.facilities[$parent.$index]
var facilities = {
"0": 56,
"1": 13,
"2": 49,
"3": 3,
"4": 11,
"5": 7,
"6": 19,
"7": 4,
"8": 9,
"9": 131,
"10": 21
};
// create an array having values contained in `facilities`
var arr = Object.keys(facilities).map(function(prop, index) {
return facilities[prop]
});
console.log(arr)
function containsAny(source, target) {
console.log("contains called");
var result = source.filter(function(item) {
return target.indexOf(item) > -1
});
return (result.length > 0);
}
// pass `arr` as second parameter to `containsAny`
var res = containsAny(checkedFacility, arr);
console.log(res)
Your function is failing on:
target.indexOf(item)
because target in your example is an Object and not an Array, so you can't call indexOf function.
So you are most likely getting:
Uncaught TypeError: target.indexOf is not a function
To solve that, you have to pass an Array as target instead of passing an Object.

Dynamically fill multidimensional array with arrays

I've been doing some research and am not getting anywhere. I have a situation where I need an array to contain a possibly variable number of arrays. Based on the example below, do you have any ideas?
var masterArray = [];
function PrepData(inVal) {
var amt = inVal.split("|");
for (var i = 0; i < amt.length; i++) {
// !!!Trouble area!!!
masterArray[i].push = amt[i];
};
}
What I'm doing is feeding 12 months' worth of data into this function, so PrepData runs 12 times each time I activate the calling function. The variable inVal can contain something like "9|9|0" or "9|123|470|1500|13". What I'm looking to do is split the incoming value on the pipe and store the results in amt. Then I want to feed each value from amt into individual arrays within masterArray. The good news is that inVal's length is constant once the first value is in, so if the first of 12 iterations splits into 3 pieces, the other 11 will also. To lay it out, here's what I would expect a typical run to produce given this input:
Oct: "1|2|1300"
Nov: "1|3|1400"
Dec: "2|5|1450"
Jan: "3|6|1900"
Feb: "4|8|2015"
Mar: "4|8|2020"
Apr: "19|38|3200"
May: "30|42|3500"
Jun: "32|50|5000"
Jul: "48|72|6300"
Aug: "50|150|7500"
Sep: "80|173|9000"
Once all twelve run through PrepData, I should have an array that contains this:
masterArray[0] == {1, 1, 2, 3, 4, 4, 19, 30, 32, 48, 50, 80} // All the numbers from the first section
masterArray[1] == {2, 3, 5, 6, 8, 8, 38, 42, 50, 72, 150, 173} // All the numbers from the second section
masterArray[2] == {1300, 1400, 1450, 1900, 2015, 2020, 3200, 3500, 5000, 6300, 7500, 9000} // All the numbers from the third section
If each month contained a string with 5 sections, then masterArray would need to be able to go from [0] to [4], and so on. The trouble area above isn't working, so I'm obviously missing something, but don't know what that might be.
Here is the updated code
var masterArray = [];
function PrepData(inVal){
var amt = inVal.split("|");
for (i in amt) {
if(typeof masterArray[i] == 'undefined'){
masterArray[i] = [];
}
masterArray[i].push(amt[i]);
}
}
There is a need to check first if an array is defined in each index in masterArray. If it's not defined then you need to initialize it to a blank array. Then you can push the splited value and you get the same result
masterArray[0] == {1, 1, 2, 3, 4, 4, 19, 30, 32, 48, 50, 80}
masterArray[1] == {2, 3, 5, 6, 8, 8, 38, 42, 50, 72, 150, 173}
masterArray[2] == {1300, 1400, 1450, 1900, 2015, 2020, 3200, 3500, 5000, 6300, 7500, 9000}
Here is a demo in js fiddle

Split a string array into a number array in javascript

I am reading a value from a dropdown list depending on what option is selected. I am using jqPlot to graph the values.
jqPlot expects an array of values like [91, 6, 2, 57, 29, 40, 95]
but when I read the value in from the dropdown box it is coming in as a whole string "[91, 6, 2, 57, 29, 40, 95]"
I tried splitting it but I got ["91", "6", "2", "57", "29", "40", "95"] which wont display the graph correctly.
Is there anybody that has encountered something like this before and what can I do to make my values convert into a number array.
Thanks for any help
You can use JSON.parse() to convert that string into a JavaScript array. The numbers in the string are not quoted so the array will also contain numbers. And you can delete all the code that parses the string as you won't need it anymore.
>>> JSON.parse("[91, 6, 2, 57, 29, 40, 95]")
[91, 6, 2, 57, 29, 40, 95]
If you need to support legacy browsers, add json2.js to shim JSON support in browsers not supporting it natively.
You can use JSON.parse to change the string "[91, 6, 2, 57, 29, 40, 95]" into an array:
​(function(){
var a = '[1,2,3]';
var b = JSON.parse('[1,2,3]');
alert(b +'\n'+ typeof(b)+'\n'+ b[0] );
})()​
Demo
As you are using jQuery you can do
$.parseJSON("[91, 6, 2, 57, 29, 40, 95]");
you can use
str.slice(1, -1).split(',').map(function(s){return parseInt(s, 10);});

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