Arithmetic Operators

Syntax

a + b, a - b, a * b, a / b, a % b, a ** b

Examples

console.log(10 + 5);  // 15
console.log(10 - 5);  // 5
console.log(10 * 5);  // 50
console.log(10 / 5);  // 2
console.log(10 % 3);  // 1 (remainder)
console.log(2 ** 3);  // 8 (2 to the power of 3)

let count = 5;
count++; // count is now 6
count--; // count is now 5 again

console.log(1 + 1);     // 2 (numeric addition)
console.log("1" + 1);   // "11" (string concatenation)
console.log("5" - 1);   // 4 (- forces numeric conversion)

Best practices

• Be careful with + when mixing strings and numbers - it concatenates rather than adds if either side is a string
• Use Number() or parseInt()/parseFloat() to explicitly convert strings to numbers before arithmetic when the source is uncertain
• Prefer x += 1 or x++ consistently within a codebase for readability
• Watch for floating-point precision issues (e.g., 0.1 + 0.2 !== 0.3) when comparing decimal results directly

At a glance

Purpose

Application logic and interaction

File extension

.js · .mjs

Runs in

Browsers and JavaScript runtimes

Usually used with

HTML, CSS and Web APIs

Specifications & further reading

• ECMAScript specification

Related JavaScript documentation