Atomics.and()
This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.
The static Atomics
.and()
method computes a bitwise AND with a given value at a given position in the array, and returns the old value at that position. This atomic operation guarantees that no other write happens until the modified value is written back.
Syntax
Atomics.and(typedArray, index, value)
Parameters
typedArray
- A shared integer typed array. One of
Int8Array
,Uint8Array
,Int16Array
,Uint16Array
,Int32Array
, orUint32Array
. index
- The position in the
typedArray
to compute the bitwise AND. value
- The number to compute the bitwise AND with.
Return value
The old value at the given position (typedArray[index]
).
Exceptions
- Throws a
TypeError
, iftypedArray
is not one of the allowed integer types. - Throws a
TypeError
, iftypedArray
is not a shared typed array type. - Throws a
RangeError
, ifindex
is out of bounds in thetypedArray
.
Description
The bitwise AND operation only yields 1, if both a
and b
are 1. The truth table for the AND operation is:
a |
b |
a & b |
---|---|---|
0 | 0 | 0 |
0 | 1 | 0 |
1 | 0 | 0 |
1 | 1 | 1 |
For example, a bitwise AND of 5 & 1
results in 0001
which is 1 in decimal.
5 0101 1 0001 ---- 1 0001
Examples
var sab = new SharedArrayBuffer(1024); var ta = new Uint8Array(sab); ta[0] = 5; Atomics.and(ta, 0, 1); // returns 0, the old value Atomics.load(ta, 0); // 1
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript Shared Memory and Atomics The definition of 'Atomics.and' in that specification. |
Draft | Initial definition. |
Browser compatibility
Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic support | No support [2] | No support | 46 (46) [1] | No support | No support | No support |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | No support | No support | 46.0 (46) [1] | No support | No support | No support |
[1] This feature is disabled by a preference setting. In about:config, set javascript.options.shared_memory
to true
.
[2] The implementation is under development and needs these runtime flags: --js-flags=--harmony-sharedarraybuffer --enable-blink-feature=SharedArrayBuffer
See also
License
© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/javascript/reference/global_objects/atomics/and