ArrayBuffer
物件是一種表示通用、固定大小的原始二進制資料緩衝。想要直接操作一個 ArrayBuffer
物件的內容是不可能的。若要讀寫該緩衝的內容則必須透過視圖,可以選擇建立一個 DataView
視圖物件或是一個限定其成員為某種型別的 TypedArray
視圖物件,它們皆能以特定的型別解讀、修改 ArrayBuffer
。
語法
new ArrayBuffer(length)
參數
length
- 要建立的緩衝陣列大小,以位元組(byte)計算。
回傳值
為一個新建立的指定大小 ArrayBuffer
物件,其內容皆初始化為 0。
說明
The ArrayBuffer
constructor creates a new ArrayBuffer
of the given length in bytes.
從既有的資料取得 ArrayBuffer
屬性
ArrayBuffer.length
- The
ArrayBuffer
constructor's length property whose value is 1. get ArrayBuffer[@@species]
- The constructor function that is used to create derived objects.
ArrayBuffer.prototype
- Allows the addition of properties to all
ArrayBuffer
objects.
方法
ArrayBuffer.isView(arg)
- Returns
true
ifarg
is one of the ArrayBuffer views, such astyped array objects
or aDataView
. Returnsfalse
otherwise. ArrayBuffer.transfer(oldBuffer [, newByteLength])
-
Returns a new
ArrayBuffer
whose contents are taken from theoldBuffer
's data and then is either truncated or zero-extended bynewByteLength
.
ArrayBuffer
實例
所有的 ArrayBuffer
物件實例皆繼承自 ArrayBuffer.prototype
.
屬性
- ArrayBuffer.prototype.constructor
- Specifies the function that creates an object's prototype. The initial value is the standard built-in
ArrayBuffer
constructor. ArrayBuffer.prototype.byteLength
Read only- 陣列大小,以位元組(byte)計算。此屬性在陣列建立之後就不可能改變了。唯讀。
方法
ArrayBuffer.prototype.slice()
- Returns a new
ArrayBuffer
whose contents are a copy of thisArrayBuffer
's bytes frombegin
, inclusive, up toend
, exclusive. If eitherbegin
orend
is negative, it refers to an index from the end of the array, as opposed to from the beginning.
範例
In this example, we create a 8-byte buffer with a Int32Array
view referring to the buffer:
var buffer = new ArrayBuffer(8); var view = new Int32Array(buffer);
規範
Specification | Status | Comment |
---|---|---|
Typed Array Specification | Obsolete | Superseded by ECMAScript 6. |
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'ArrayBuffer' in that specification. |
Standard | Initial definition in an ECMA standard. Specified that new is required. |
ECMAScript 2017 Draft (ECMA-262) The definition of 'ArrayBuffer' in that specification. |
Draft |
瀏覽器相容性
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | 7.0 | 4.0 (2) | 10 | 11.6 | 5.1 |
ArrayBuffer() without new throws |
? | 44 (44) | ? | ? | ? |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | 4.0 | (Yes) | 4.0 (2) | 10 | 11.6 | 4.2 |
ArrayBuffer() without new throws |
? | ? | 44.0 (44) | ? | ? | ? |
相容性備註
Starting with ECMAScript 2015, ArrayBuffer
constructors require to be constructed with a new
operator. Calling an ArrayBuffer
constructor as a function without new
, will throw a TypeError
from now on.
var dv = ArrayBuffer(10); // TypeError: calling a builtin ArrayBuffer constructor // without new is forbidden
var dv = new ArrayBuffer(10);