JavaScript: Exponentiation Operator (In-Depth)

The exponentiation operator (**) is a mathematical operator that raises the left operand to the power of the right operand. Introduced in ES2016 (ES7), it is the standard way to perform exponentiation in modern JavaScript.

Basic Usage

let squared = 5 ** 2;    // 25
let cubed = 2 ** 3;      // 8
let root = 16 ** 0.5;    // 4 (square root)
    

Equivalent to Math.pow()

The ** operator is functionally identical to Math.pow():

let value1 = 3 ** 4;            // 81
let value2 = Math.pow(3, 4);    // 81
    

Operator Precedence and Associativity

• The ** operator is right-associative: evaluated from right to left.
• This means a ** b ** c is a ** (b ** c).

let result = 2 ** 3 ** 2; // 2 ** (3 ** 2) => 2 ** 9 = 512
    

Negative Numbers

Use parentheses with negative bases to avoid confusion:

let a = (-2) ** 3; // -8
let b = -2 ** 3;   // - (2 ** 3) = -8
    

Assignment Operator **=

JavaScript also supports the exponentiation assignment operator (**=):

let x = 10;
x **= 2; // x = x ** 2 = 100
    

Practical Examples

• Calculate powers, roots, or exponential growth.
• Quickly square/cube numbers or arrays of numbers with map().

let arr = [1, 2, 3, 4];
let squares = arr.map(n => n ** 2); // [1, 4, 9, 16]
    

Summary

• Use ** for powers, roots, and exponents.
• It's clear, concise, and now the standard in JavaScript.
• Remember the right-associativity and use parentheses for clarity with negatives or multiple exponents.