Question

I use the following function to dynamically check the properties of a variable number of objects.

// FUNCTION: Check Objects
var ObjectsN = 4;
function CheckObjects()
{
        for (var i=0; i<=ObjectsN; i++)
        {
            if ((eval("Object"+i+".property")==0)
            {
                if (i==ObjectsN)
                {
                    alert("Function finished");
                }
            }
            else
            {
                return; // end function
            }
        }
}

I need to check if each object has the same property value.
Is there a way to do the same without using eval ?
A real example would be really much appreciated.

Answer 1

The structure you’re looking for is an Array. So use an array to store your objects:

/* assuming `var Object1 = new Object(), Object2 = new Object();` and so on */
var objs = [ Object1, Object2, Object3 ];

Then testing for a property should implement hasOwnProperty while iterating:

for (var o = 0; i < objs.length; o++){
  if (objs[o].hasOwnProperty('property')){
    // Property exists, test its value:
  }
}

You could then test against objs[o].property to retrieve its value and see if it matches what you’re expecting.

And for those browsers that may not have the function available, here is a cross-browser version of hasOwnProperty (source, but originally from here):

/*
Cross-browser hasOwnProperty solution, based on answers from:
https://stackoverflow.com/questions/135448/how-do-i-check-to-see-if-an-object-has-an-attribute-in-javascript
*/
if ( !Object.prototype.hasOwnProperty ) {
  Object.prototype.hasOwnProperty = function(prop) {
    var proto = obj.__proto__ || obj.constructor.prototype;
    return (prop in this) && (!(prop in proto) || proto[prop] !== this[prop]);
  };
}