JavaScript - swap two variables

In this article, we would like to show you how to swap two variables in JavaScript.

Quick solution:

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[a, b] = [b, a];

In this example, we use destructuring assignment to swap values of a and b variables.

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var a = 1;

var b = 2;

​

[a, b] = [b, a];

​

console.log(a); // 2

console.log(b); // 1

In this example, we use tmp temporary variable to swap a and b variables in three steps:

1. assign the value of a variable to the tmp,
2. assign a variable with the value of b,
3. assign b variable with the value of tmp (which have the initial value of a).

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var a = 1;

var b = 2;

var tmp;

​

tmp = a;

a = b;

b = tmp;

​

console.log(a); // 2

console.log(b); // 1

In this example, we use addition and subtraction to swap values of a and b variables.

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var a = 1;

var b = 2;

​

a = a + b;

b = a - b;

a = a - b;

​

console.log(a); // 2

console.log(b); // 1

In this example, we use the XOR operator to swap values of a and b variables.

Note: With this solution, you can swap only integers.

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var a = 1; // 0001

var b = 2; // 0010

​

a = a ^ b; // 0011

b = a ^ b; // 0001

a = a ^ b; // 0010

​

console.log(a); // 2

console.log(b); // 1

XOR operator:

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┌─────┬─────┬───────┐

│  a  │  b  │ a ^ b │

├─────┼─────┼───────┤

│  0  │  0  │   0   │

│  1  │  1  │   0   │

│  0  │  1  │   1   │

│  1  │  0  │   1   │

└─────┴─────┴───────┘

1. JavaScript - bitwise XOR operator

2. JavaScript - array destructuring with rest parameter

1. Bitwise XOR (^) - JavaScript | MDN
2. Destructuring assignment - JavaScript | MDN