Addition (+) - JavaScript 编辑

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

Browser compatibility

BCD tables only load in the browser

See also

• Subtraction operator
• Division operator
• Multiplication operator
• Remainder operator
• Exponentiation operator
• Increment operator
• Decrement operator
• Unary negation operator
• Unary plus operator