How to create a dynamic object in a loop?

Question

Basically I want to create one large object of many object in JavaScript. Something like:

var objects = {}
for (x)
objects.x = {name: etc}

Any ideas?

This is very confusing. Answer this: What are you looping over and what is your intended result. State your input and your desired output. — Alex Wayne, Mar 04 '10 at 23:29
This question relates to my other question here: http://stackoverflow.com/questions/2375143/problem-with-tojson-and-json-decode-in-php-and-js I tried passing it as an array of objects but its somehow not working, so I'm trying this method. Something like: ManyObjects: { Object1 : {name:etc, x:etc}, Object2 : {name:etc, x:etc}} — mike, Mar 04 '10 at 23:55

score 93 · Accepted Answer · answered Mar 04 '10 at 23:33

93

var objects = {};

for (var x = 0; x < 100; x++) {
  objects[x] = {name: etc};
}

answered Mar 04 '10 at 23:33

Tomalak

332,285
67
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John K · Answer 2 · 2010-03-04T23:44:10.720

An actual implementation

Populate a container object with 100 other objects.

<script>
var container = { }; // main object

// add 100 sub-object values
for(i = 0; i < 100; ++i) {
 container['prop'+i ]  /*property name or key of choice*/
         = { 'a':'something', 
             'b':'somethingelse', 
             'c': 2 * i
           }; 
}

TEST THE Results - iterate and display objects...

for(var p in container) {
 var innerObj = container[p];
 document.write('<div>container.' + p + ':' + innerObj + '</div>');
 // write out properties of inner object
 document.write('<div> .a: ' + innerObj['a'] + '</div>');
 document.write('<div> .b: ' + innerObj['b'] + '</div>');
 document.write('<div> .c: ' + innerObj['c'] + '</div>');
}
</script>

Output is like

container.prop0:[object Object]
.a: something
.b: somethingelse
.c: 0
container.prop1:[object Object]
.a: something
.b: somethingelse
.c: 2
container.prop2:[object Object]
.a: something
.b: somethingelse
.c: 4

etc...

score 8 · Answer 3 · answered Sep 25 '21 at 18:19

Using object[propertyname] is the same as using object.propertyname and hence we can dynamically create object keys with object[propertyname] format
for eg:

var fruits = ["Apple", "Orange", "Banana","Grapes"];
var colors = ["red", "Orange", "yellow","blue"];
var newObj = {};
for (var i = 0; i < fruits.length; i++) {
  newObj[fruits[i]] = colors[i];
}
console.log(newObj);

score 6 · Answer 4 · edited Jun 16 '14 at 19:45

6

Try this

var objects = new Array();
var howmany = 10;

for (var i = 0; i < howmany; i++)
{
    objects[i] = new Object();

}

edited Jun 16 '14 at 19:45

Fortin

152
2
14

answered Mar 04 '10 at 23:47

streetparade

32,000
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You have a leaking global `i` variable. Don't forget to use `var`. – Eli Grey Mar 05 '10 at 00:50
Do not use **new Array()** and **new Object()** as it is not efficient performance wise. Instead use the literals. – Zaheen Oct 29 '17 at 08:37

score 1 · Answer 5 · answered Apr 05 '22 at 19:14

//On Nested Obj like that
var playersCount = {
    "Players" : {}
}

var exempleCount = 5;

for(i=0; i <= exempleCount;i++){
    var BadID = Math.floor(Math.random() * 10000);
  
        playersCount.Players["Player_"+i] = {
            "id":BadID, 
            "xPos":0, 
            "yPos":0, 
            "zPos":0
        };
    }
  console.log(playersCount);

How to create a dynamic object in a loop?

5 Answers5

An actual implementation

Linked

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