Web/JavaScript/Reference/Operators/Decrement

The decrement operator (--) decrements (subtracts one from) its operand and returns a value.

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Syntax

Operator: x-- or --x

Description

If used postfix, with operator after operand (for example, x--), the decrement operator decrements and returns the value before decrementing.

If used prefix, with operator before operand (for example, --x), the decrement operator decrements and returns the value after decrementing.

Examples

Postfix decrement

let x = 3;
y = x--;

// y = 3
// x = 2

Prefix decrement

let a = 2;
b = --a;

// a = 1
// b = 1

Specifications

Specification

ECMAScript (ECMA-262)The definition of 'Decrement operator' in that specification.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
Decrement (`--`)	Chrome Full support 2	Edge Full support 12	Firefox Full support 1	IE Full support 3	Opera Full support 3	Safari Full support 4	WebView Android Full support 1	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 3.2	Samsung Internet Android Full support 1.0	nodejs Full support 0.1.100

Legend

Full support: Full support