Web/JavaScript/Reference/Operators/Addition

The addition operator (+) produces the sum of numeric operands or string concatenation.

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Syntax

Operator: x + y

Examples

Numeric addition

// Number + Number -> addition
1 + 2 // 3

// Boolean + Number -> addition
true + 1 // 2

// Boolean + Boolean -> addition
false + false // 0

String concatenation

// String + String -> concatenation
'foo' + 'bar' // "foobar"

// Number + String -> concatenation
5 + 'foo' // "5foo"

// String + Boolean -> concatenation
'foo' + false // "foofalse"

Specifications

Specification

ECMAScript (ECMA-262)The definition of 'Addition 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
Addition (`+`)	Chrome Full support 1	Edge Full support 12	Firefox Full support 1	IE Full support 3	Opera Full support 3	Safari Full support 1	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 1	Samsung Internet Android Full support 1.0	nodejs Full support 0.1.100

Legend

Full support: Full support