Array.prototype.each = function(callback) { for (var i = 0; i < this.length; i++) callback(this[i]); } - is this ok?

Question

Array.prototype.each = function(callback) { for (var i = 0; i < this.length; i++) callback(this[i]); } - is this ok?

I know it's a matter of taste, but for my taste using for loop each time I want to iterate over array is bad. So I came up with this:

Array.prototype.each = function(callback) {
  for (var i = 0; i < this.length; i++)
    callback(this[i]);
}

Now I can do:

[10, 20, 30].each(function(n) { console.log(n/10) })

Later I found some tips on the Internet that suggested this approach, but I still wonder if it's free from side effects. It seems very obvious, and that is what worries me :)

I'm not using any library like jQuery or Prototype. I'm coding for Node.js.

javascript
arrays
node.js
iteration
prototype

Answer 1

I suggest you use forEach. It's implemented in most modern browsers, and the shim is provided by MDN.

On node.js, it's implemented (it uses V8, same engine as Chrome), so you don't need a shim.

Its use is something like the following:

arr.forEach( function( el ) {
    // play with "el"
} )

Also, I suggest you look at the new array methods provided by ES5:

Answer 2

This does have a pretty big side effect

If we now run the following code

a = [10, 20, 30];
for (var i in a) {
    console.log(i + ": " + a[i]);
}

And check the console output, we see this:

0: 10
1: 20
2: 30
each: function (callback) {
  for (var i = 0; i < this.length; i++)
    callback(this[i]);
}

Which restricts the type of for loop you can do on an array to

a = [10, 20, 30];
for (var i = 0; i < a.length; ++i) {
    console.log(a[i] + ": " + a[i]);
}