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Subtraction assignment (-=)

The -= operator performs subtraction on the two operands and assigns the result to the left operand.

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Syntax

js
x -= y

Description

x -= y is equivalent to x = x - y, except that the expression x is only evaluated once.

Examples

Using subtraction assignment

js
let bar = 5;

bar -= 2; // 3
bar -= "foo"; // NaN

let foo = 3n;
foo -= 2n; // 1n

Specifications

Specification
ECMAScript Language Specification
# sec-assignment-operators

Browser compatibility

Desktop Mobile Server
Chrome Edge Firefox Opera Safari Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet WebView Android Deno Node.js
Subtraction_assignment 1 12 1 3 1 18 4 10.1 1 1.0 4.4 1.0 0.10.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Subtraction_assignment