Question

A few people I work with include on their sites some javascript I wrote and host. But some of those sites use prototype.js or some other framework and its causing some big problems.

For example:

var test = {"one":[{"a":"b"}]};
for (var i in test.one) { console.log(i); }

The expected result of this would be “0” in the console (i being the key to that array)

But if I go to a site like prototypejs.org and run the same code in firebug’s console, I get a list of all the prototype junk (each, eachSlice, etc..)

Try running it in your console here on stackoverflow, it returns “0” as expected.

How do I prevent this? Any good workarounds?

Answer 1

Either test that each property you enumerate is NOT in the prototype

for (var i in test.one) { 
   if (test.one.hasOwnProperty(i)) {
      console.log(i); 
   }
}

or don’t enumerate arrays.

for (var i = 0, ii = test.one.length; i < ii; i++) {
     console.log(i);
}

Any code that extends Object.prototype is not your problem. You should not have to guard against that.