Fruited introduction to Array

in Javascript

Alex Girard

Types

Number // 0, 1, .5

String // 'some text', "surrounded by quotes"

Boolean // true, false

Object

Function

Array

Date

RegExp

/* List or collection of values grouped together */

undefined

Syntax


    var fruits           = ['apple', 'orange', 'grappes', 'peach', 'apricot'];

    var examResults      = new Array(15, 12, 7, 16);

    var allocateForLater = new Array(10);

    var empty            = [];

    var mix              = ['Alex', 29, true, ['blue', 180, 76] ];

Accessing elements


    var fruits           = ['apple', 'orange', 'grappes', 'peach', 'apricot'];

    
    fruits[0] == 'apple' // true

    fruits[2] == 'grappes' // true

    fruits[5] == 'apricot' // false

    
    fruits.length // 5

    fruits.indexOf('apple') // 0

    fruits.indexOf('peach') // 3

    fruits.lastIndexOf('apple') // 0

    
 // Get last element of the array

    fruits[fruits.length-1] === 'apricot' // true

Loop through


    var fruits           = ['apple', 'orange', 'grappes', 'peach', 'apricot'];

    
    for(var i=0, l=fruits.length; i<l; ++i){
    
        console.log( fruits[i] ); //print the value at index i
   
    }

Uber useful


    var fruits           = ['apple', 'orange', 'grappes', 'peach', 'apricot'];

    fruits.length === 5 // true
    
    fruits.push('cherry', 'beans');

    fruits.length === 7 // true

    // Oups

    fruits.pop()

    fruits // ['apple', 'orange', 'grappes', 'peach', 'apricot', 'cherry']

Advanced juggling


    var fruits           = ['apple', 'orange', 'grappes', 'peach', 'apricot'];


    fruits.shift() // 'apple'

    fruits // ['orange', 'grappes', 'peach', 'apricot']

    // Explanation: pop the first element of the array


    fruits.splice(1, 1) // ['grappes']

    fruits // ['orange', 'peach', 'apricot']

    // Explanation: remove element(s) given a starting index, and a number of elements


    // end of course...

    fruits.slice(1, 3) // ['peach', 'apricot']

    // Explanation: take begin and end indexes, but exclude the last one of end.
    // Note that it doesn't mutate the array.

Ressources

Fruited introduction to Array

By Alexandre Girard

Fruited introduction to Array

This slides present the array type in Javascript, and what methods we can apply on them. It is recommended to be familiar with the other javascript types, and have access to the Chrome console to test the given code.

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