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# Chapter 8. Methods

Though this be madness, yet there is method in 't.

William Shakespeare, The Tragedy of Hamlet, Prince of Denmark

JavaScript includes a small set of standard methods that are available on the standard types.

Array
array.concat(item...)

The `concat` method produces a new array containing a shallow copy of this `array` with the `item`s appended to it. If an `item` is an array, then each of its elements is appended individually. Also see `array``.push(``item``...)` later in this chapter.

```var a = ['a', 'b', 'c'];
var b = ['x', 'y', 'z'];
var c = a.concat(b, true);
// c is ['a', 'b', 'c', 'x', 'y', 'z', true]```
array.join(separator)

The `join` method makes a string from an `array` . It does this by making a string of each of the `array` 's elements, and then concatenating them all together with a `separator` between them. The default `separator` is `','`. To join without separation, use an empty string as the `separator`.

If you are assembling a string from a large number of pieces, it is usually faster to put the pieces into an array and `join` them than it is to concatenate the pieces with the `+` operator:

```var a = ['a', 'b', 'c'];
a.push('d');
var c = a.join('');    // c is 'abcd';```
array.pop( )

The `pop` and `push` methods make an `array` work like a stack. The `pop` method removes and returns the last element in this `array` . If the `array` is `empty`, it returns `undefined`.

```var a = ['a', 'b', 'c'];
var c = a.pop(  );    // a is ['a', 'b'] & c is 'c'```

`pop` can be implemented like this:

`Array.method('pop', function ( ) { return this.splice(this.length ...`

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