What is Atomics?
- Atomics are used with SharedArrayBuffer(generic fixed-length binary data buffer) objects.
- Atomics are not constructors like other global objects.
- Atomics cannot be used with a new operator or can be invoked as a function.
Multiple threads can read and write the same data in memory when there is shared memory. To ensure that predicted values are written and read accurately, another operation cannot start until and unless the current one finishes. Atomic operations also cannot be interrupted.
Among the Atomic Operations, there is a method Atomics.sub() that is used to subtract a given value at a given position in the array and returns the old value at that position. No other write operation can happen until the modified value is written back.
Atomics.sub(typedArray, index, value)
- typedarray: It is the shared integer typed array you want to modify.
- index: It is the position in the typedArray from where you want to subtract a value from.
- value : It is the number of you want to subtract.
Return Value: Atomics.sub() returns the old value at the given position (typedArray[index]).
Examples of the above function are provided below.
Input : arr = 9; Atomics.sub(arr, 0, 3); Output : 9
Input : arr = 3; Atomics.sub(arr, 0, 2); Output : 3
Codes for the above function are provided below.
- If the typedArray is not one of the allowed integer types then the Atomics.sub() operation throws a TypeError.
- If the typedArray is not a shared typed array then the Atomics.sub() operation throws a TypeError.
- If the index used as an argument to the Atomics.sub() operation is out of the bound in the typedArray then the Atomics.sub() operation throws a RangeError.
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