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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.exchange() method exchanges 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.exchange(typedArray, index, value)
Parameters
typedArray- A shared integer typed array. One of
Int8Array,Uint8Array,Int16Array,Uint16Array,Int32Array, orUint32Array. index- The position in the
typedArrayto exchange avalue. value- The number to exchange.
Return value
The old value at the given position (typedArray[index]).
Exceptions
- Throws a
TypeError, iftypedArrayis not one of the allowed integer types. - Throws a
TypeError, iftypedArrayis not a shared typed array type. - Throws a
RangeError, ifindexis out of bounds in thetypedArray.
Examples
var sab = new SharedArrayBuffer(1024); var ta = new Uint8Array(sab); Atomics.exchange(ta, 0, 12); // returns 0, the old value Atomics.load(ta, 0); // 12
Specifications
| Specification | Status | Comment |
|---|---|---|
| ECMAScript Shared Memory and Atomics The definition of 'Atomics.exchange' 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