Question

I’ve started working with Qunit to do unit testing on my code, but am striking problems comparing objects.

The code I’m testing dynamically creates an object:

var fields = ['id','name'];
var result = {};
for (var field in fields)
{
    var name = fields[field];
    result[name] = name;
}

var expected = { id : 'id', name : 'name' };

test(expected, result, "same ?");

This test fails, and I can see that while expected just contains the fields id and name, result also contains a whole lot of functions, eg

"function (iterator, context) {...

I think these functions come from me treating the object like an array in order to assign to it.

Is there a way to strip these functions out (or prevent them from getting added in the first place)?

I was thinking of doing

result = $.parseJSON($.toJSON(result));

is there a better way?

Answer 1

You can check the type of each object in the collection to see if it’s a function:

if(typeof fields[field] == 'function') continue;

Also, don’t use for..in on arrays:

for(var i = 0; i < fields.length; i++) {
   result[result[i]] = result[i];
}

What you have there isn’t strictly an object, it’s an Array object, which is nevertheless an object, but not in the sense that it has key-value pairs.

If you use a vanilla for loop, you will not iterate through the prototype chain as you do with for..in, so maybe doing that might solve your problem.