Removing content/items from an array

gistfile1.js

/*
 * When you delete an array element using the delete
 * operator, the array length is not affected. For example
 * if you delete arr[2], arr[3] is still arr[3] and arr[2]
 * is undefined.
 */

arr = ['a', 'b', 'c', 'd']
// ["a", "b", "c", "d"]
delete arr[2]
// true
arr
// ["a", "b", undefined, "d"]


/*
 * One technique for removing content is to use the splice
 * method to rebuild the array (adding new elements while
 * removing old elements).
 */

arr = ['a', 'b', 'c', 'd']
// ["a", "b", "c", "d"]
arr.splice(2, 1)
// ["c"]
arr
// ["a", "b", "d"]


/*
 * Another technique John Resig came up with extends the
 * native prototype for the Array constructor by adding a
 * remove method.
 */

Array.prototype.remove = function(from, to) {
  var rest = this.slice((to || from) + 1 || this.length);
  this.length = from < 0 ? this.length + from : from;
  return this.push.apply(this, rest);
};

// Remove the second item from the array
arr = ['a', 'b', 'c', 'd']
// arr = ['a', 'b', 'c', 'd']
arr.remove(2);
// 3
arr
// ["a", "b", "d"]

// Remove the second-to-last item from the array
arr = ['a', 'b', 'c', 'd']
// arr = ['a', 'b', 'c', 'd']
arr.remove(-2);
// 3
arr
// ["a", "b", "d"]

// Remove the second and third items from the array
arr = ['a', 'b', 'c', 'd']
// arr = ['a', 'b', 'c', 'd']
arr.remove(1,2);
// 2
arr
// ["a", "d"]

// Remove the last and second-to-last items from the array
arr = ['a', 'b', 'c', 'd']
// arr = ['a', 'b', 'c', 'd']
arr.remove(-2,-1);
// 2
arr
// ["a", "b"]


/*
 * And finally, a jQuery technique that uses the grep method
 * and removes an array item based on it's string value instead
 * of index
 */

arr = ['a', 'b', 'c', 'd']
// ["a", "b", "c", "d"]
arr = $.grep(arr, function(value) { return value != 'c'; });
// ["a", "b", "d"]