js Arrays

Arrays

Arrays are zero-indexed lists of values. They are a handy way to store a set of related items of the same type (such as strings), though in reality, an array can include multiple types of items, including other arrays.

Example 2.25: A simple array

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var myArray = [ 'hello', 'world' ];

Example 2.26: Accessing array items by index

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var myArray = [ 'hello', 'world', 'foo', 'bar' ];

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console.log(myArray[3]);   // logs 'bar'

Example 2.27: Testing the size of an array

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var myArray = [ 'hello', 'world' ];

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console.log(myArray.length);   // logs 2

Example 2.28: Changing the value of an array item

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var myArray = [ 'hello', 'world' ];

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myArray[1] = 'changed';

While it's possible to change the value of an array item as shown in “Changing the value of an array item”, it's generally not advised.

Example 2.29: Adding elements to an array （增加元素到数组）

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var myArray = [ 'hello', 'world' ];

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myArray.push('new');

Example 2.30: Working with arrays

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var myArray = [ 'h', 'e', 'l', 'l', 'o' ];

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var myString = myArray.join('');   // 'hello'

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var mySplit = myString.split('');  // [ 'h', 'e', 'l', 'l', 'o' ]