Mastering JavaScript

Data Structures and Manipulation
The sort() method sorts the elements of an array:
var myArray = new Array("A", "C", "B");
myArray.sort();
// sorts the array so that myArray = [ "A","B","c" ]
The sort() method can optionally take a callback function to define how the
elements are compared. The function compares two values and returns one of three
values. Let us study the following functions:
• indexOf(searchElement[, fromIndex]): This searches the array for
searchElement and returns the index of the first match:
var a = ['a', 'b', 'a', 'b', 'a','c','a'];
console.log(a.indexOf('b')); // 1
// Now try again, starting from after the last match
console.log(a.indexOf('b', 2)); // 3
console.log(a.indexOf('1')); // -1, 'q' is not found
• lastIndexOf(searchElement[, fromIndex]): This works like indexOf(),
but only searches backwards:
var a = ['a', 'b', 'c', 'd', 'a', 'b'];
console.log(a.lastIndexOf('b')); // 5
// Now try again, starting from before the last match
console.log(a.lastIndexOf('b', 4)); // 1
console.log(a.lastIndexOf('z')); // -1
Now that we have covered JavaScript arrays in depth, let me introduce you to a
fantastic library called Underscore.js (http://underscorejs.org/). Underscore.js
provides a bunch of exceptionally useful functional programming helpers to make
your code even more clear and functional.
We will assume that you are familiar with Node.js; in this case, install Underscore.js
via npm:
npm install underscore
As we are installing Underscore as a Node module, we will test all the examples by
typing them in a .js file and running the file on Node.js. You can install Underscore
using Bower also.
Like jQuery's $ module, Underscore comes with a _ module defined. You will call all
functions using this module reference.
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