Have you extended a Native lately? It's an incredibly helpful thing. Often people write ugly functions that take a string or whatever as an argument and return some manipulation of the string. Extending natives is a great way to do the same thing, but it is much prettier (aka: explicit, readable, easier-to-debug.)

I've seen stuff like this:

fn1(fn2(10, fn3('house')));

Hard to figure out what's happening. Instead you can write code like:

fn3('house').fn2(10).fn1();

I've used this in a couple scripts, it takes a number and returns a string with zeros padded in front: 123 becomes '000123'. Really handy for filenames and the like. Here's the ugly version:

function zeroPad(num, zeros){
  zeros = zeros || 3;
  var str = '' + num;
  zeros.times(function(){ str = '0'+str; });
  return str;
};

// usage
doSomething(zeroPad(document.getElementById('myInput').value, 3));

Number.implement({
  zeroPad: function(zeros){
    var str = '' + this;
    zeros.times(function(){ str = '0'+str; });
    return str;
  }
});

// so that it works on both numbers and strings
String.implement({
  zeroPad: function(zeros){
      return this.toInt().zeroPad(zeros);
  }
});

// usage
$('myInput').get('value').zeroPad(3).doSomething();

doSomething(zeroPad(document.getElementById('myInput').value, 3));
// vs
$('myInput').get('value').zeroPad(3).doSomething();

Awesome? Yes. You can do the same thing to:

• Array
• Function
• Number
• String
• Hash

Some say extending natives is a bad idea. Personally, I think it's awesome--but this topic is a sore spot for some. Extending natives is a feature of javascript itself that any general application framework like MooTools is entitled to use. There could be an entire article dedicated to this topic but this article isn't it. This article is simply here to show how to use this handy feature.

Arian Stolwijk created this amazing gem: Array.Math. Code samples often tell the story faster:

[2,5,1,6].sum(); // 14
[2,5,6,2].product(3); // [6,15,18,6]
[9,12,15].quotient(3) // [3,4,5]

This is all made possible by extending the Array native, see?

Array.implement({

        sum: function(start,length){
            var sum = 0, 
                start = start ? start : 0,
                length = length ? length : this.count()-start;
            length = start ? length + 2 : length;
            for(var i=start;i<length;i++) sum += this[i];
            return sum;
        },

        product: function(p){
            var arr = $type(p) == 'array';
            return this.map(function(entity,i){
                return arr ? (entity * p[i]) : (entity * p);
            });
        },

        quotient: function(q){
            var arr = $type(q) == 'array';
            return this.map(function(entity,i){
                return arr ? (entity / q[i]) : (entity / q);
            });
        },

        // and a whole lot more awesome ...

    });

• this is the number or string, or whatever, when inside the method.
• Return something that makes sense (usually this).
• You can implement several methods all in the same code block.

This is just one more great tool to help keep your code organized and readable.

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