Atomics.or()

静态方法 Atomics.or() 用数组中指定位置的值进行一次按位或运算,并返回未计算时数组中指定位置处的值。这个atomic操作保证了在修改后的值被写回之前没有其它的写入操作发生。

Syntax

Atomics.or(typedArray, index, value)

参数

typedArray
一个共享的int数组,类型为 Int8ArrayUint8ArrayInt16ArrayUint16ArrayInt32ArrayUint32Array
index
typedArray 中要进行按位或运算的索引。
value
要进行按位或运算的数。

返回值

typedArray[index] 处运算前的值。

异常

  • 若 typedArray 不是一个可用的int类型,则抛出一个 TypeError 异常。
  • 若 typedArray 不是一个共享的数组类型,则抛出一个 TypeError 异常。
  • 若 index 索引超出了 typedArray 的大小,则抛出一个 RangeError 异常。

详情

当 a 或者 b 为1时,按位或运算结果为1。或运算真值表如下:

a b a | b
0 0 0
0 1 1
1 0 1
1 1 1

例如,让 5 & 1 进行按位或运算的结果是 0101 ,也就是十进制的5:

5  0101
1  0001
   ----
5  0101

示例

var sab = new SharedArrayBuffer(1024);
var ta = new Uint8Array(sab);
ta[0] = 2;

Atomics.or(ta, 0, 1); // returns 2, the old value
Atomics.load(ta, 0);  // 3

规范

规范 状态 注释
ECMAScript Latest Draft (ECMA-262)
Atomics.or
Draft Initial definition in ES2017.

浏览器兼容性

Update compatibility data on GitHub
DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
orChrome Full support 68
Full support 68
No support 60 — 63
Notes
Notes Chrome disabled SharedArrayBuffer on January 5, 2018 to help reduce the efficacy of speculative side-channel attacks. This was a temporary removal while mitigations were put in place.
Edge No support 16 — 17
Notes
No support 16 — 17
Notes
Notes Support was removed to mitigate speculative execution side-channel attacks (Windows blog).
Firefox Full support 57
Notes Disabled
Full support 57
Notes Disabled
Notes Support was disabled by default to mitigate speculative execution side-channel attacks (Mozilla Security Blog).
Disabled From version 57: this feature is behind the javascript.options.shared_memory preference (needs to be set to true). To change preferences in Firefox, visit about:config.
No support 55 — 57
No support 46 — 55
Disabled
Disabled From version 46 until version 55 (exclusive): this feature is behind the javascript.options.shared_memory preference (needs to be set to true). To change preferences in Firefox, visit about:config.
IE No support NoOpera No support NoSafari No support 10.1 — ?WebView Android No support 60 — 63
Notes
No support 60 — 63
Notes
Notes Chrome disabled SharedArrayBuffer on January 5, 2018 to help reduce the efficacy of speculative side-channel attacks. This is intended as a temporary measure until other mitigations are in place.
Chrome Android No support 60 — 63
Notes
No support 60 — 63
Notes
Notes Chrome disabled SharedArrayBuffer on January 5, 2018 to help reduce the efficacy of speculative side-channel attacks. This is intended as a temporary measure until other mitigations are in place.
Firefox Android Full support 57
Notes Disabled
Full support 57
Notes Disabled
Notes Support was disabled by default to mitigate speculative execution side-channel attacks (Mozilla Security Blog).
Disabled From version 57: this feature is behind the javascript.options.shared_memory preference (needs to be set to true). To change preferences in Firefox, visit about:config.
No support 55 — 57
No support 46 — 55
Disabled
Disabled From version 46 until version 55 (exclusive): this feature is behind the javascript.options.shared_memory preference (needs to be set to true). To change preferences in Firefox, visit about:config.
Opera Android No support NoSafari iOS No support NoSamsung Internet Android No support No
Notes
No support No
Notes
Notes Chrome disabled SharedArrayBuffer on January 5, 2018 to help reduce the efficacy of speculative side-channel attacks. This is intended as a temporary measure until other mitigations are in place.
nodejs Full support 8.10.0

Legend

Full support  
Full support
No support  
No support
See implementation notes.
See implementation notes.
User must explicitly enable this feature.
User must explicitly enable this feature.

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