Can I create dynamic object names in JavaScript? [duplicate]

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javascript - dynamic variables
Dynamic Javascript variable names

I need to create a number of objects on a page and want to name them sequentially. Is there a way to do this in JavaScript?

for (i=0;i<num;i++){
  var obj+i = new myObject("param1","param2");
  obj+i.someProperty = value;
}

This way I can dynamically create a varying number of objects (dependent on the value "num") and then set their properties appropriately.

I can do this in PHP, is there a way to do it in JavaScript?

Thank you for helping! I resisted the whole idea of creating an array of objects, hadn't done that before. I asked the question thinking that it would help me to start a dialog to figure out an answer. After receiving the array answer again, I gave it a try, and it worked! Sorry for being so slow in believing that. — Terry Carnes
– Terry Carnes, Commented Oct 12, 2012 at 18:28

Trevor Dixon · Accepted Answer · 2012-10-10 18:54:45Z

14

This isn't recommended, but does what you're trying to do (if you're running in a browser and not some other js environment).

for (i = 0; i < num; i++) {
  window['obj' + i] = new myObject("param1","param2");
  window['obj' + i].someProperty = value;
}
obj0.someProperty;

This works because global variables are actually properties of the window object (if you're running in the browser). You can access properties of an object using either dot notation (myObject.prop) or bracket notation (myObject['prop']). By assigning window['obj' + i], you're creating a global variable named 'obj' + i.

The better option is to use an array or parent object to store your objects.

myObjs = {};
for (i = 0; i < num; i++) {
  myObjs['obj' + i] = new myObject("param1","param2");
  myObjs['obj' + i].someProperty = value;
}
myObjs.obj0.someProperty;

Or use an array like lots of other answers suggest.

edited Oct 10, 2012 at 18:54

answered Oct 10, 2012 at 18:45

Trevor Dixon

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2 Comments

Webbies Over a year ago

i agree, the above code works. But don't do it!

Felix Kling Over a year ago

I think it's important to point out that these variables will be global then.

Felix Kling · Accepted Answer · 2012-10-10 18:44:20Z

7

That's what arrays are for, to hold a collection of something:

var objs = [];
for (i=0;i<num;i++){
  objs[i] = new myObject("param1","param2");
  objs[i].someProperty = value;
}

Dynamic variables are almost always a bad idea.

answered Oct 10, 2012 at 18:44

Felix Kling

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Comments

Anoop · Accepted Answer · 2012-10-10 18:42:24Z

0

You can create, and you can set/modify properties of that object.

Modified code:

var obj = {}; //
for (i=0;i<num;i++){
  obj[i] = new myObject("param1","param2");
  obj[i].someProperty = value;
}

I recommend you to use array. as

 var obj = []; //
    for (i=0;i<num;i++){
      obj[i] = new myObject("param1","param2");
      obj[i].someProperty = value;
    }

answered Oct 10, 2012 at 18:42

Anoop

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1 Comment

Craicerjack Over a year ago

I know this is old but this doesnt create a dynamic object name.

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