一元負號運算子（-）
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since 2015年7月.
一元負號運算子（-）置於運算元之前，並將運算元轉為其負值。
嘗試一下
const x = 4;
const y = -x;
console.log(y);
// Expected output: -4
const a = "4";
const b = -a;
console.log(b);
// Expected output: -4
語法
js
-x
範例
轉換數字
js
const x = 3;
const y = -x;
// y = -3
// x = 3
轉換非數字
一元負號運算子可以將非數字轉為數字。
js
const x = "4";
const y = -x;
// y = -4
規範
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-unary-minus-operator |
瀏覽器相容性
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