JavaScript - Swap Two Variables in JavaScript
Last Updated :
02 Apr, 2025
Improve
In this article, we will learn about swapping 2 variables with Various Approaches.
Using destructing Assignment - Most Used
Here, we will be using a destructing Assignment. The destructing assignment makes it possible to unpack values from an array, object, or other properties into distinct variables.
let a = 40;
let b = 30;
console.log(`before swap a= ${a}`);
console.log(`before swap b= ${b}`);
// a would be swapped to b and b would be swapped to a
[b, a] = [a, b];
console.log(`after swap a= ${a}`);
console.log(`after swap b= ${b}`);
let a = 40;let b = 30;console.log(`before swap a= ${a}`);console.log(`before swap b= ${b}`);// a would be swapped to b and b would be swapped to a[b, a] = [a, b];console.log(`after swap a= ${a}`);console.log(`after swap b= ${b}`);Output
before swap a= 40 before swap a= 30 after swap a= 30 after swap a= 40
Using Temporary variable
- Let's say we create a temp variable that stores the value of a variable A.
- Then we copy the value of B to A (A would be overwritten).
- Then we copy the value of temp to B (earlier value of A).
let a = 20;
let b = 10;
let temp;
console.log(`before swapping: a= ${a}`);
console.log(`before swapping b= ${b}`);
temp = a;
a = b;
b = temp;
console.log(`after swapping a= ${a}`);
console.log(`after swapping b= ${b}`);
let a = 20;let b = 10;let temp;console.log(`before swapping: a= ${a}`);console.log(`before swapping b= ${b}`);temp = a;a = b;b = temp;console.log(`after swapping a= ${a}`);console.log(`after swapping b= ${b}`);Output
before swapping: a= 20 before swapping b= 10 after swapping a= 10 after swapping b= 20
Using Arithmetic Operations
- Firstly, we add a + b to a (a would be greater than b as it is).
- Now we subtract b from a so the value of b is now available to b
- Now we subtract a with b again to a so a will have the value of B
let a = 10;
let b = 20;
console.log(`before swap a= ${a}`);
console.log(`before swap b= ${b}`);
a = a + b;//10=10+20 now a would be 30
b = a - b;//20=30-20 now b would be 10
a = a - b;//30=30-10 so a would be now 20
console.log(`after swap a= ${a}`);
console.log(`after swap b= ${b}`);
let a = 10;let b = 20;console.log(`before swap a= ${a}`);console.log(`before swap b= ${b}`);a = a + b;//10=10+20 now a would be 30b = a - b;//20=30-20 now b would be 10a = a - b;//30=30-10 so a would be now 20console.log(`after swap a= ${a}`);console.log(`after swap b= ${b}`);Output
before swap a= 10 before swap b= 20 after swap a= 20 after swap b= 10
Using XOR Bitwise Operator
the XOR bitwise operation is used to swap the values without the need for a temporary variable. This method takes advantage of the property that a ^ b ^ b is equal to a.
let a = 5;
let b = 10;
console.log("Before swapping: a =", a, "b =", b);
a = a ^ b;
b = a ^ b;
a = a ^ b;
console.log("After swapping: a =", a, "b =", b);
let a = 5;let b = 10;console.log("Before swapping: a =", a, "b =", b);a = a ^ b;b = a ^ b;a = a ^ b;console.log("After swapping: a =", a, "b =", b);Output
Before swapping: a = 5 b = 10 After swapping: a = 10 b = 5
