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Atomics.or( ) In JavaScript

What is Atomics?
The Atomics is an object in JavaScript which provides atomic operations to be performed as static methods. Just like the Math object in JavaScript, all the properties and methods of Atomics are also static.
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.

Atomics Operations in JavaScript
Multiple threads can read and write the same data in memory when there shared memory is. 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.

Atomics.and() Method
Among the Atomic Operations, there is a method Atomics.or() that is used to compute a bitwise OR operation with a given value at a given position in an array. The old value at that position is returned by the Atomics.or() function. No other write operation can happen until the modified value is written back.

Syntax:

Atomics.or(typedArray, index, value)

Parameters Used:



  1. typedarray : It is the shared integer typed array you want to modify.
  2. index : It is the position in the typedArray where you want to compute bitwise OR.
  3. value : It is the number you want to compute the bitwise OR with.

Return Value:
Atomics.or() returns the old value at the given position (typedArray[index]).

Examples for the above function are provided below.

Examples:

Input : arr[0] = 9;
        Atomics.or(arr, 0, 3);
Output : 9

Input : arr[0] = 3; 
        Atomics.or(arr, 0, 2);
Output : 3

Codes for the above function are provided below.
Code 1:

<script>
<!-- creating a SharedArrayBuffer -->
var buf = new SharedArrayBuffer(25);
var arr = new Uint8Array(buf);
  
<!-- Initialising element at zeroth position of array with 9 -->
arr[0] = 9;
  
<!-- 9 (1001) OR 3 (0011) =  11 (1011) -->
<!-- Displaying the return value of the Atomics.or() method -->
console.log(Atomics.or(arr, 0, 3));
  
<!-- Displaying the updated SharedArrayBuffer -->
console.log(Atomics.load(arr, 0));
</script>

OUTPUT:

9
11

Code 2:

<script>
<!-- creating a SharedArrayBuffer -->
var buf = new SharedArrayBuffer(25);
var arr = new Uint8Array(buf);
<!-- Initialising element at zeroth position of array with 3 -->
arr[0] = 3;
  
<!-- 3 (0011) AND 2 (0010) =  3 (0011) -->
<!-- Displaying the return value of the Atomics.or() method -->
console.log(Atomics.or(arr, 0, 2));
  
<!-- Displaying the updated SharedArrayBuffer -->
console.log(Atomics.load(arr, 0));
</script>

OUTPUT:

3
3

Exceptions :

  • Throws a TypeError, if typedArray is not one of the allowed integer types.
  • Throws a TypeError, if typedArray is not a shared typed array type.
  • Throws a RangeError, if the index is out of bounds in the typedArray.


This article is attributed to GeeksforGeeks.org

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