Addition assignment (+=)
The addition assignment operator (+=
) adds the value of the right operand to a variable and assigns the result to the variable. The types of the two operands determine the behavior of the addition assignment operator. Addition or concatenation is possible.
Syntax
x += y // x = x + y
Examples
Using addition assignment
// Assuming the following variables
// foo = 'foo'
// bar = 5
// baz = true
// Number + Number -> addition
bar += 2 // 7
// Boolean + Number -> addition
baz += 1 // 2
// Boolean + Boolean -> addition
baz += false // 1
// Number + String -> concatenation
bar += 'foo' // "5foo"
// String + Boolean -> concatenation
foo += false // "foofalse"
// String + String -> concatenation
foo += 'bar' // "foobar"
Specifications
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
Addition_assignment |
1 |
12 |
1 |
3 |
3 |
1 |
1 |
18 |
4 |
10.1 |
1 |
1.0 |
See also
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https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Addition_assignment