Increment (++) - JavaScript 编辑

The increment operator (++) increments (adds one to) its operand and returns a value.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

Syntax

Operator: x++ or ++x

Description

If used postfix, with operator after operand (for example, x++), the increment operator increments and returns the value before incrementing.

If used prefix, with operator before operand (for example, ++x), the increment operator increments and returns the value after incrementing.

Examples

Postfix increment

let x = 3;
y = x++;

// y = 3
// x = 4

Prefix increment

let a = 2;
b = ++a;

// a = 3
// b = 3

Specifications

Browser compatibility

BCD tables only load in the browser

See also

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