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Dynamically create instance fields for a JavaScript object

I have a dynamically created list of strings called "variables". I need to use these lines as instance variables for an array of JavaScript objects.

var objectsArr = []; function obj(){}; for (var i=0; i<someNumberOfObjects; i++ ) { ... objectsArr[i] = new Object(); for (var j=0; j<variables.length; j++) { objectArr[i].b = 'something'; //<--this works, but... //objectArr[i].variables[j] = 'something'; //<---this is what I want to do. } }

The recorded line shows what I'm trying to do.

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Console syntax can be used to manage a property by name:

 objectArr[i][variables[j]] = 'something';

In other words, get the object from objectArr in index i , then find the field named variables[j] and set this value to 'something' .

In general terms, this object is o :

 var o = {};

You can set the property by name:

 o['propertyName'] = 'value';

And access it in the usual way:

 alert(o.propertyName);
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Use parenthesis notation. This will be done:

 var objectsArr = [], ii, jj; function Obj() {} for(ii = 0; ii < someNumberOfObjects; ii += 1) { objectsArr[ii] = new Obj(); for (jj = 0; jj < variables.length; jj += 1) { objectArr[ii][variables[jj]] = 'something'; } }

A few additional notes:

  • Javascript has no block scope, so you must have two separate loop variables.
  • By convention, constructor functions, such as Obj , must start with a capital letter to indicate that they should be used with the new keyword. However, in this case, if you do not need objects for the non-Object prototype, you can simply use a simple object literal ( objectsArr[ii] = {}; ).
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