Массивы
Javascript поддерживает два вида структуры "массив":
- Ассоциативный массив (хеш), где данные хранятся по произвольному ключу.
Об этом читайте в разделе Объекты.
- Числовой массив
Array , где данные хранятся по номерам.
Он описан в этой статье.
Javascript - очень гибкий язык, поэтому технически в Array можно хранить произвольные ключи, как в Object . Но лучше использовать типы по назначению.
Для хранения данных по номеру предназначен тип Array .
var arr = new Array()
arr.test = 5
arr[1] = "blabla"
...
В типе Array есть специальные методы, ориентированные именно на работу с числовыми ключами.
Есть два эквивалентных способа создания массива:
var a = new Array()
var a = []
Или, сразу со значениями
var a = new Array("a", 1, true)
var a = ["a", 1, true]
Эти способы работают одинаково, кроме объявления вида new Array(10) , когда у конструктора есть единственный аргумент-число.
Такое объявление создаст пустой массив (все элементы undefined) длиной 10 . По возможности, не используйте new Array .
Отсчет элементов начинается с нуля:
alert(a[0]) // => "a"
Массив хранит данные по численным ключам, но внутри он использует точно такой же хэш (ту же структуру данных), как и обычный объект, поэтому можно сделать так:
var a = []
a[1] = 1
a[999999] = 2
и массив a будет занимать память, нужную для хранения этих двух соответствий, а не займет длинный непрерывный кусок памяти, как это произошло бы в языке С.
У каждого массива есть свойство length , которое автоматом меняется при каждом обновлении массива. Длина массива - это не количество элементов, а максимальный целый ключ + 1:
alert(a.length) // всего 2 элемента, но выведет 1000000
Добавлять новый элемент можно эквивалентными вызовами
a[a.length] = "new element"
a.push("new element")
Перебор элементов обычно (когда индексы непрерывные) осуществляется простым циклом:
var arr = [ "array", "elements", "here" ]
for(var i=0; i<arr.length; i++) {
... сделать что-то с arr[i] ...
}
Если индексы - с разрывами, то перебор осуществляется так же, как в объектах:
var arr = []
arr[1] = 123
arr[9999] = 456
for(var i in arr) {
if (!arr.hasOwnProperty(i)) continue;
... сделать что-то с arr[i] ...
}
В массиве есть всё необходимое, чтобы работать с ним как с очередью или со стеком, или и с тем и другим одновременно.
Методы push и pop добавляют или вынимают значение с конца массива
var arr = [3,5,7]
arr.push(9)
var last = arr.pop() //= 9
var last = arr.pop() // = 7
alert(arr.length) // = 2
Методы shift /unshift делают то же самое, с начала массива.
var arr = [4,6,8]
arr.unshift(2) // arr = [2,4,6,8]
arr.unshift(0) // arr = [0,2,4,6,8]
var last = arr.shift() // last = 0, arr = [2,4,6,8]
arr.shift() // arr = [4,6,8]
shift/ unshift обычно приводят к перенумерации всего массива. shift сдвигает все элементы на единицу влево, а unshift - вправо. Поэтому на больших массивах эти методы работают медленнее, чем push /pop.

slice(begin[, end])
Возвращает подмассив с индексами begin…end .
splice(index, deleteCount[, element1,…, elementN])
Удалить deleteCount элементов, начиная с index, и вставить на их место element1…elementN
Есть и еще много методов:
О них можно почитать на английском, например, в http://developer.mozilla.org/en/..Array
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Есть многомерный массив:
Как к каждому подмассиву присоединить соответствующий аудиофайл, чтобы при вызове он звучал?
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