TypedArray | JavaScript

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描述
构造函数
静态特性
静态方法
实例特性
实例方法
范例
规范
浏览器兼容性
另请参阅
相关话题

A TypedArray object describes an array-like view of an underlying binary data buffer . There is no global property named TypedArray , nor is there a directly visible TypedArray constructor. Instead, there are a number of different global properties, whose values are typed array constructors for specific element types, listed below. On the following pages you will find common properties and methods that can be used with any typed array containing elements of any type.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

描述

ECMAScript 2015 defines a TypedArray constructor that serves as the [[Prototype]] of all TypedArray constructors. This constructor is not directly exposed: there is no global %TypedArray% or TypedArray property. It is only directly accessible through Object.getPrototypeOf(Int8Array) and similar. All TypedArray s constructors inherit common properties from the %TypedArray% constructor function. Additionally, all typed array prototypes ( TypedArray. prototype ) have %TypedArray%.prototype as their [[Prototype]] .

%TypedArray% constructor on its own is not particularly useful. Calling it or using it in a new expression will throw a TypeError , except when used during object creation in JS engines that support subclassing. There are at present no such engines, so %TypedArray% is only useful to polyfill functions or properties onto all TypedArray 构造函数。

When creating an instance of a TypedArray (e.g. Int8Array ), an array buffer is created internally in memory or, if an ArrayBuffer object is given as constructor argument, then this is used instead. The buffer address is saved as an internal property of the instance and all the methods of % TypedArray %.prototype , i.e. set value and get value etc., operate on that array buffer address.

TypedArray objects

Type	值范围	Size in bytes	描述	Web IDL 类型	Equivalent C type
`Int8Array`	`-128` to `127`	1	8-bit two's complement signed integer	`byte`	`int8_t`
`Uint8Array`	`0` to `255`	1	8-bit unsigned integer	`octet`	`uint8_t`
`Uint8ClampedArray`	`0` to `255`	1	8-bit unsigned integer (clamped)	`octet`	`uint8_t`
`Int16Array`	`-32768` to `32767`	2	16-bit two's complement signed integer	`short`	`int16_t`
`Uint16Array`	`0` to `65535`	2	16-bit unsigned integer	`unsigned short`	`uint16_t`
`Int32Array`	`-2147483648` to `2147483647`	4	32-bit two's complement signed integer	`long`	`int32_t`
`Uint32Array`	`0` to `4294967295`	4	32-bit unsigned integer	`unsigned long`	`uint32_t`
`Float32Array`	`1.2` × `10 ^-38` to `3.4` × `10 ³⁸`	4	32-bit IEEE floating point number (7 significant digits e.g., `1.1234567` )	`unrestricted float`	`float`
`Float64Array`	`5.0` × `10 ^-324` to `1.8` × `10 ³⁰⁸`	8	64-bit IEEE floating point number (16 significant digits e.g., `1.123...15` )	`unrestricted double`	`double`
`BigInt64Array`	`-2 ⁶³` to `2 ⁶³ -1`	8	64-bit two's complement signed integer	`bigint`	`int64_t (signed long long)`
`BigUint64Array`	`0` to `2 ⁶⁴ -1`	8	64-bit unsigned integer	`bigint`	`uint64_t (unsigned long long)`

构造函数

This object cannot be instantiated directly. Instead, you create an instance of an array of a particular type, such as a Int8Array 或 BigInt64Array . These objects all have a common syntax for their constructors:

new TypedArray();
new TypedArray(length);
new TypedArray(typedArray);
new TypedArray(object);
new TypedArray(buffer [, byteOffset [, length]]);

Where TypedArray is a constructor for one of the concrete types.

参数

length: When called with a length argument, an internal array buffer is created in memory, of size length multiplied by BYTES_PER_ELEMENT bytes, containing zeros.
typedArray: When called with a typedArray argument, which can be an object of any of the typed array types (such as Int32Array ), the typedArray gets copied into a new typed array. Each value in typedArray is converted to the corresponding type of the constructor before being copied into the new array. The length of the new typed array will be same as the length of the typedArray 自变量。
object: When called with an object argument, a new typed array is created as if by the TypedArray .from() 方法。
buffer , byteOffset , length: When called with a buffer , and optionally a byteOffset 和 length argument, a new typed array view is created that views the specified ArrayBuffer 。 byteOffset and length parameters specify the memory range that will be exposed by the typed array view. If both are omitted, all of buffer is viewed; if only length is omitted, the remainder of buffer is viewed.

静态特性

TypedArray.BYTES_PER_ELEMENT: Returns a number value of the element size for the different TypedArray 对象。
TypedArray.name: Returns the string value of the constructor name (e.g, "Int8Array" ).
get TypedArray[@@species]
TypedArray.prototype: Prototype for TypedArray 对象。

静态方法

TypedArray.from(): 创建新的 TypedArray from an array-like or iterable object. See also Array.from() .
TypedArray.of(): 创建新的 TypedArray with a variable number of arguments. See also Array.of() .

实例特性

TypedArray.prototype.buffer: 返回 ArrayBuffer referenced by the typed array. Fixed at construction time and thus read only .
TypedArray.prototype.byteLength: Returns the length (in bytes) of the typed array. Fixed at construction time and thus read only.
TypedArray.prototype.byteOffset: Returns the offset (in bytes) of the typed array from the start of its ArrayBuffer . Fixed at construction time and thus read only.
TypedArray.prototype.length: Returns the number of elements held in the typed array. Fixed at construction time and thus read only.

实例方法

TypedArray.prototype.copyWithin(): Copies a sequence of array elements within the array. See also Array.prototype.copyWithin() .
TypedArray.prototype.entries(): 返回新的 Array Iterator object that contains the key/value pairs for each index in the array. See also Array.prototype.entries() .
TypedArray.prototype.every(): Tests whether all elements in the array pass the test provided by a function. See also Array.prototype.every() .
TypedArray.prototype.fill(): Fills all the elements of an array from a start index to an end index with a static value. See also Array.prototype.fill() .
TypedArray.prototype.filter(): Creates a new array with all of the elements of this array for which the provided filtering function returns true 。另请参阅 Array.prototype.filter() .
TypedArray.prototype.find(): Returns the found value in the array, if an element in the array satisfies the provided testing function, or undefined if not found. See also Array.prototype.find() .
TypedArray.prototype.findIndex(): Returns the found index in the array, if an element in the array satisfies the provided testing function or -1 if not found. See also Array.prototype.findIndex() .
TypedArray.prototype.forEach(): Calls a function for each element in the array. See also Array.prototype.forEach() .
TypedArray.prototype.includes(): Determines whether a typed array includes a certain element, returning true or false as appropriate. See also Array.prototype.includes() .
TypedArray.prototype.indexOf(): Returns the first (least) index of an element within the array equal to the specified value, or -1 if none is found. See also Array.prototype.indexOf() .
TypedArray.prototype.join(): Joins all elements of an array into a string. See also Array.prototype.join() .
TypedArray.prototype.keys(): 返回新的 Array Iterator that contains the keys for each index in the array. See also Array.prototype.keys() .
TypedArray.prototype.lastIndexOf(): Returns the last (greatest) index of an element within the array equal to the specified value, or -1 if none is found. See also Array.prototype.lastIndexOf() .
TypedArray.prototype.map(): Creates a new array with the results of calling a provided function on every element in this array. See also Array.prototype.map() .
TypedArray.prototype.reduce(): Apply a function against an accumulator and each value of the array (from left-to-right) as to reduce it to a single value. See also Array.prototype.reduce() .
TypedArray.prototype.reduceRight(): Apply a function against an accumulator and each value of the array (from right-to-left) as to reduce it to a single value. See also Array.prototype.reduceRight() .
TypedArray.prototype.reverse(): Reverses the order of the elements of an array — the first becomes the last, and the last becomes the first. See also Array.prototype.reverse() .
TypedArray.prototype.set()
TypedArray.prototype.slice(): Extracts a section of an array and returns a new array. See also Array.prototype.slice() .
TypedArray.prototype.some(): 返回 true if at least one element in this array satisfies the provided testing function. See also Array.prototype.some() .
TypedArray.prototype.sort(): Sorts the elements of an array in place and returns the array. See also Array.prototype.sort() .
TypedArray.prototype.subarray(): 返回新的 TypedArray from the given start and end element index.
TypedArray.prototype.values(): 返回新的 Array Iterator object that contains the values for each index in the array. See also Array.prototype.values() .
TypedArray.prototype.toLocaleString(): Returns a localized string representing the array and its elements. See also Array.prototype.toLocaleString() .
TypedArray.prototype.toString(): Returns a string representing the array and its elements. See also Array.prototype.toString() .
TypedArray.prototype[@@iterator](): 返回新的 Array Iterator object that contains the values for each index in the array.

范例

New is required

Starting with ECMAScript 2015, TypedArray constructors must be constructed with the new operator. Calling a TypedArray constructor as a function without new will throw a TypeError .

var dv = Int8Array([1, 2, 3]);
// TypeError: calling a builtin Int8Array constructor
// without new is forbidden

var dv = new Int8Array([1, 2, 3]);

Property access

You can reference elements in the array using standard array index syntax (that is, using bracket notation). However, getting or setting indexed properties on typed arrays will not search in the prototype chain for this property, even when the indices are out of bound. Indexed properties will consult the ArrayBuffer and will never look at object properties. You can still use named properties, just like with all objects.

// Setting and getting using standard array syntax
var int16 = new Int16Array(2);
int16[0] = 42;
console.log(int16[0]); // 42
// Indexed properties on prototypes are not consulted (Fx 25)
Int8Array.prototype[20] = 'foo';
(new Int8Array(32))[20]; // 0
// even when out of bound
Int8Array.prototype[20] = 'foo';
(new Int8Array(8))[20]; // undefined
// or with negative integers
Int8Array.prototype[-1] = 'foo';
(new Int8Array(8))[-1]; // undefined
// Named properties are allowed, though (Fx 30)
Int8Array.prototype.foo = 'bar';
(new Int8Array(32)).foo; // "bar"

规范

规范
ECMAScript (ECMA-262) The definition of 'TypedArray Objects' in that specification.

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
`TypedArray`	Chrome 7	Edge 12	Firefox 4	IE 10	Opera 11.6	Safari 5.1	WebView Android 4	Chrome Android 18	Firefox Android 4	Opera Android 12	Safari iOS 4.2	Samsung Internet Android 1.0	nodejs 0.10
`BYTES_PER_ELEMENT`	Chrome 7	Edge 12	Firefox 4	IE 10	Opera 11.6	Safari 5.1	WebView Android 4	Chrome Android 18	Firefox Android 4	Opera Android 12	Safari iOS 4.2	Samsung Internet Android 1.0	nodejs 0.10
`buffer`	Chrome 7	Edge 14	Firefox 4	IE 10	Opera 11.6	Safari 5.1	WebView Android 4	Chrome Android 18	Firefox Android 4	Opera Android 12	Safari iOS 4.2	Samsung Internet Android 1.0	nodejs 0.10
`byteLength`	Chrome 7	Edge 14	Firefox 4	IE 10	Opera 11.6	Safari 5.1	WebView Android 4	Chrome Android 18	Firefox Android 4	Opera Android 12	Safari iOS 4.2	Samsung Internet Android 1.0	nodejs 0.10
`byteOffset`	Chrome 7	Edge 14	Firefox 4	IE 10	Opera 11.6	Safari 5.1	WebView Android 4	Chrome Android 18	Firefox Android 4	Opera Android 12	Safari iOS 4.2	Samsung Internet Android 1.0	nodejs 0.10
Constructor without arguments	Chrome 7	Edge 12	Firefox 55	IE 10	Opera 11.6	Safari 5.1	WebView Android ≤37	Chrome Android 18	Firefox Android 55	Opera Android 12	Safari iOS 5	Samsung Internet Android 1.0	nodejs 0.10
`copyWithin`	Chrome 45	Edge 14	Firefox 34	IE No	Opera 36	Safari 9.1	WebView Android No	Chrome Android No	Firefox Android 34	Opera Android No	Safari iOS 9.3	Samsung Internet Android No	nodejs 4.0.0
`entries`	Chrome 45	Edge 14	Firefox 37	IE No	Opera 36	Safari No	WebView Android No	Chrome Android 45	Firefox Android 37	Opera Android No	Safari iOS No	Samsung Internet Android 5.0	nodejs 0.12
`every`	Chrome 45	Edge 14	Firefox 37	IE No	Opera 36	Safari No	WebView Android No	Chrome Android 45	Firefox Android 37	Opera Android No	Safari iOS No	Samsung Internet Android 5.0	nodejs 4.0.0
`fill`	Chrome 45	Edge 14	Firefox 37	IE No	Opera 36	Safari No	WebView Android No	Chrome Android 45	Firefox Android 37	Opera Android No	Safari iOS No	Samsung Internet Android 5.0	nodejs 4.0.0
`filter`	Chrome 45	Edge 14	Firefox 38	IE No	Opera No	Safari No	WebView Android No	Chrome Android 45	Firefox Android 38	Opera Android No	Safari iOS No	Samsung Internet Android 5.0	nodejs 4.0.0
`find`	Chrome 45	Edge 14	Firefox 37	IE No	Opera 32	Safari No	WebView Android 45	Chrome Android 45	Firefox Android 37	Opera Android 32	Safari iOS No	Samsung Internet Android 5.0	nodejs 4.0.0
`findIndex`	Chrome 45	Edge 14	Firefox 37	IE No	Opera 32	Safari No	WebView Android 45	Chrome Android 45	Firefox Android 37	Opera Android 32	Safari iOS No	Samsung Internet Android 5.0	nodejs 4.0.0
`forEach`	Chrome 45	Edge 14	Firefox 38	IE No	Opera 32	Safari 10	WebView Android 45	Chrome Android 45	Firefox Android 38	Opera Android 32	Safari iOS 10	Samsung Internet Android 5.0	nodejs 4.0.0
`from`	Chrome 45	Edge 14	Firefox 38	IE No	Opera No	Safari 10	WebView Android No	Chrome Android No	Firefox Android 38	Opera Android No	Safari iOS 10	Samsung Internet Android No	nodejs 4.0.0
`includes`	Chrome 47	Edge 14	Firefox 43	IE No	Opera 34	Safari 10	WebView Android No	Chrome Android 47	Firefox Android 43	Opera Android 34	Safari iOS 10	Samsung Internet Android 5.0	nodejs 6.0.0 6.0.0 5.0.0 Disabled Disabled From version 5.0.0: this feature is behind the `--harmony` runtime flag.
Indexed properties not consulting prototype	Chrome 7 7 Negative integers are not considered as indexed properties and therefore return the value of the prototype property.	Edge 12 12 Negative integers are not considered as indexed properties and therefore return the value of the prototype property.	Firefox 25	IE 10 10 Negative integers are not considered as indexed properties and therefore return the value of the prototype property.	Opera 11.6 11.6 Negative integers are not considered as indexed properties and therefore return the value of the prototype property.	Safari 5.1 5.1 Negative integers are not considered as indexed properties and therefore return the value of the prototype property.	WebView Android ≤37 ≤37 Negative integers are not considered as indexed properties and therefore return the value of the prototype property.	Chrome Android 18 18 Negative integers are not considered as indexed properties and therefore return the value of the prototype property.	Firefox Android 25	Opera Android 12 12 Negative integers are not considered as indexed properties and therefore return the value of the prototype property.	Safari iOS 5 5 Negative integers are not considered as indexed properties and therefore return the value of the prototype property.	Samsung Internet Android 1.0 1.0 Negative integers are not considered as indexed properties and therefore return the value of the prototype property.	nodejs 0.10 0.10 Negative integers are not considered as indexed properties and therefore return the value of the prototype property.
`indexOf`	Chrome 45	Edge 14	Firefox 37 37 Starting with Firefox 47, this method will no longer return `-0` 。例如， `new Uint8Array([0]).indexOf(0, -0)` will now always return `+0` .	IE No	Opera 32	Safari No	WebView Android No	Chrome Android 45	Firefox Android 37 37 Starting with Firefox 47, this method will no longer return `-0` 。例如， `new Uint8Array([0]).indexOf(0, -0)` will now always return `+0` .	Opera Android 32	Safari iOS No	Samsung Internet Android 5.0	nodejs 4.0.0
Iterable in constructor	Chrome 39	Edge 14	Firefox 52	IE No	Opera 26	Safari 10	WebView Android 39	Chrome Android 39	Firefox Android 52	Opera Android 26	Safari iOS 10	Samsung Internet Android 4.0	nodejs 4.0.0
`join`	Chrome 45	Edge 14	Firefox 37	IE No	Opera 32	Safari No	WebView Android 45	Chrome Android 45	Firefox Android 37	Opera Android 32	Safari iOS No	Samsung Internet Android 5.0	nodejs 4.0.0
`keys`	Chrome 38	Edge 14	Firefox 37	IE No	Opera 25	Safari 10	WebView Android 38	Chrome Android 38	Firefox Android 37	Opera Android 25	Safari iOS 10	Samsung Internet Android 3.0	nodejs 0.12
`lastIndexOf`	Chrome 45	Edge 14	Firefox 37 37 Starting with Firefox 47, this method will no longer return `-0` 。例如， `new Uint8Array([0]).lastIndexOf(0, -0)` will now always return `+0` .	IE No	Opera 32	Safari 10	WebView Android 45	Chrome Android 45	Firefox Android 37 37 Starting with Firefox 47, this method will no longer return `-0` 。例如， `new Uint8Array([0]).lastIndexOf(0, -0)` will now always return `+0` .	Opera Android 32	Safari iOS 10	Samsung Internet Android 5.0	nodejs 4.0.0
`length`	Chrome 7	Edge 14	Firefox 4	IE 10	Opera 11.6	Safari 5.1	WebView Android 4	Chrome Android 18	Firefox Android 4	Opera Android 12	Safari iOS 4.2	Samsung Internet Android 1.0	nodejs 0.10
`map`	Chrome 45	Edge 14	Firefox 38	IE No	Opera 32	Safari No	WebView Android 45	Chrome Android 45	Firefox Android 38	Opera Android 32	Safari iOS No	Samsung Internet Android 5.0	nodejs 4.0.0
`name`	Chrome 7	Edge 12	Firefox 4	IE 10	Opera 11.6	Safari 5.1	WebView Android 4	Chrome Android 18	Firefox Android 4	Opera Android 12	Safari iOS 4.2	Samsung Internet Android 1.0	nodejs 0.10
Named properties	Chrome 7	Edge 12	Firefox 30	IE 10	Opera 11.6	Safari 5.1	WebView Android ≤37	Chrome Android 18	Firefox Android 30	Opera Android 12	Safari iOS 5	Samsung Internet Android 1.0	nodejs 0.10
`TypedArray()` without `new` throws	Chrome 7	Edge 14	Firefox 44	IE No	Opera 15	Safari 5.1	WebView Android ≤37	Chrome Android 18	Firefox Android 44	Opera Android 14	Safari iOS 5	Samsung Internet Android 1.0	nodejs 0.12
`of`	Chrome 45	Edge 14	Firefox 38	IE No	Opera No	Safari No	WebView Android No	Chrome Android No	Firefox Android 38	Opera Android No	Safari iOS No	Samsung Internet Android No	nodejs 4.0.0
`reduce`	Chrome 45	Edge 14	Firefox 37	IE No	Opera 32	Safari 10	WebView Android 45	Chrome Android 45	Firefox Android 37	Opera Android No	Safari iOS 10	Samsung Internet Android 5.0	nodejs 4.0.0
`reduceRight`	Chrome 45	Edge 14	Firefox 37	IE No	Opera 32	Safari 10	WebView Android 45	Chrome Android 45	Firefox Android 37	Opera Android No	Safari iOS 10	Samsung Internet Android 5.0	nodejs 4.0.0
`reverse`	Chrome 45	Edge 14	Firefox 37	IE No	Opera 32	Safari 10	WebView Android 45	Chrome Android 45	Firefox Android 37	Opera Android No	Safari iOS 10	Samsung Internet Android 5.0	nodejs 4.0.0
`set`	Chrome 7	Edge 14	Firefox 4	IE 10	Opera 11.6	Safari 5.1	WebView Android 4	Chrome Android 18	Firefox Android 4	Opera Android 12	Safari iOS 4.2	Samsung Internet Android 1.0	nodejs 0.10
`slice`	Chrome 45	Edge 14	Firefox 38	IE No	Opera 32	Safari 10	WebView Android 45	Chrome Android 45	Firefox Android 38	Opera Android 32	Safari iOS 10	Samsung Internet Android 5.0	nodejs 4.0.0
`some`	Chrome 45	Edge 14	Firefox 37	IE No	Opera 32	Safari 10	WebView Android 45	Chrome Android 45	Firefox Android 37	Opera Android No	Safari iOS 10	Samsung Internet Android 5.0	nodejs 4.0.0
`sort`	Chrome 45	Edge 14	Firefox 46	IE No	Opera 32	Safari 10	WebView Android 45	Chrome Android 45	Firefox Android 46	Opera Android 32	Safari iOS 10	Samsung Internet Android 5.0	nodejs 4.0.0
`subarray`	Chrome 7	Edge 14	Firefox 4	IE 10	Opera 11.6	Safari 5.1	WebView Android 4	Chrome Android 18	Firefox Android 4	Opera Android 12	Safari iOS 4.2	Samsung Internet Android 1.0	nodejs 0.12
`toLocaleString`	Chrome 7	Edge 12	Firefox 51	IE 10	Opera 11.6	Safari 5.1	WebView Android ≤37	Chrome Android 18	Firefox Android 51	Opera Android 12	Safari iOS 5	Samsung Internet Android 1.0	nodejs 0.10
`toString`	Chrome 7	Edge 12	Firefox 51	IE 10	Opera 11.6	Safari 5.1	WebView Android ≤37	Chrome Android 18	Firefox Android 51	Opera Android 12	Safari iOS 5	Samsung Internet Android 1.0	nodejs 0.10
`值`	Chrome 38	Edge 14	Firefox 37	IE No	Opera 25	Safari 10	WebView Android 38	Chrome Android 38	Firefox Android 37	Opera Android 25	Safari iOS 10	Samsung Internet Android 3.0	nodejs 0.12
`@@iterator`	Chrome 38	Edge 12	Firefox 36 36 不支持 27 — 36 Alternate Name A placeholder property named `@@iterator` 被使用。 Alternate Name Uses the non-standard name: `@@iterator` 不支持 17 — 27 Alternate Name A placeholder property named `iterator` 被使用。 Alternate Name Uses the non-standard name: `iterator`	IE No	Opera 25	Safari 10	WebView Android 38	Chrome Android 38	Firefox Android 36 36 不支持 27 — 36 Alternate Name A placeholder property named `@@iterator` 被使用。 Alternate Name Uses the non-standard name: `@@iterator` 不支持 17 — 27 Alternate Name A placeholder property named `iterator` 被使用。 Alternate Name Uses the non-standard name: `iterator`	Opera Android 25	Safari iOS 10	Samsung Internet Android 3.0	nodejs 0.12
`@@species`	Chrome 51	Edge 13	Firefox 48	IE No	Opera 38	Safari No	WebView Android 51	Chrome Android 51	Firefox Android 48	Opera Android 41	Safari iOS No	Samsung Internet Android 5.0	nodejs 6.5.0 6.5.0 6.0.0 Disabled Disabled From version 6.0.0: this feature is behind the `--harmony` runtime flag.

图例

完整支持
不支持

用户必须明确启用此特征。

另请参阅

JavaScript 类型数组
ArrayBuffer
DataView
TextDecoder — Helper that decode strings from numerical data

元数据

最后修改： Jul 13, 2020

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描述