Syntax Sugar #4 - CoffeeScript one-liners

I'm a sucker for short, concise syntax. One of the beautiful features about CoffeeScript - the JavaScript/Ruby lovechild that I'm slowly learning to adore - is its single line function declaration. Using this powerful syntax one can write really expressive functions with terse code.

Let's demonstrate this with a quick function. Let's say we want to remove a specific element from an array. My first guess would be to write:

var arr = [ 1, 2, 3, 4 ];
delete arr[0]; // [ nil, 2, 3, 4 ]

The issue with this, of course, is that we are left with a stray nil. That's not particularly convenient if we're using the array a lot. Instead, let's write a function and patch it onto the Array class.

Array::remove = ( element ) -> 
    if (@indexOf(element)) > -1
        @splice @indexOf(element), 1

We're using the built-in splice() method to remove the element at the index of our element. That isn't such a bad first attempt, but it's not particularly terse or pleasant. Let's remove the repetition and move index's assignment into the conditional:

Array::remove = ( element ) ->
    if (index = @indexOf(element)) > -1
        @splice index, 1

We can use CoffeeScript's keyword syntax and bracketless method calling to clean it up a bit further:

Array::remove = ( element ) ->
    if (index = @indexOf element) isnt -1
        @splice index, 1

And finally we can push it all into one line:

Array::remove = ( e ) -> @splice i, 1 if (i = @indexOf e) isnt -1

If we compare this to the JavaScript it generates:

Array.prototype.remove = function(e) {
    var i;
    if ((i = this.indexOf(e)) !== -1) {
        return this.splice(i, 1);
    }
};

…it's a no-brainer. CoffeeScript is a wonderful way of making JavaScript cleaner, more concise and altogether much more pleasant to work with. I'd highly recommend downloading a copy and trying it out.