ArrayBuffer

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。

Exceptions

A RangeError is thrown if the length is larger than Number.MAX_SAFE_INTEGER (>= 2 ** 53) or negative.

說明

The ArrayBuffer constructor creates a new ArrayBuffer of the given length in bytes.

從既有的資料取得 ArrayBuffer

• From a Base64 string
• 從本地端檔案

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 if arg is one of the ArrayBuffer views, such as typed array objects or a DataView. Returns false otherwise.

ArrayBuffer.transfer(oldBuffer [, newByteLength])

Returns a new ArrayBuffer whose contents are taken from the oldBuffer's data and then is either truncated or zero-extended by newByteLength.

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 this ArrayBuffer's bytes from begin, inclusive, up to end, exclusive. If either begin or end is negative, it refers to an index from the end of the array, as opposed to from the beginning.

ArrayBuffer.slice()

Has the same functionality as ArrayBuffer.prototype.slice().

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

瀏覽器相容性

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);

參見

• TypedArray
• SharedArrayBuffer