Math.asin()
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
Math.asin()
靜態方法回傳數字的反正弦值(單位為弧度)。也就是說,
嘗試一下
// Calculates angle of a right-angle triangle in radians
function calcAngle(opposite, hypotenuse) {
return Math.asin(opposite / hypotenuse);
}
console.log(calcAngle(6, 10));
// Expected output: 0.6435011087932844
console.log(calcAngle(5, 3));
// Expected output: NaN
語法
js
Math.asin(x)
參數
x
-
一個介於 -1 到 1 之間(包含邊界)的數字,表示角度的正弦值。
回傳值
x
的反正弦值(單位為弧度,範圍介於 和 之間,包含邊界)。如果 x
小於 -1 或大於 1,則回傳 NaN
。
描述
由於 asin()
是 Math
的靜態方法,你必須使用 Math.asin()
來呼叫它,而非呼叫你建立的 Math
物件的方法(Math
並非建構子)。
範例
使用 Math.asin()
js
Math.asin(-2); // NaN
Math.asin(-1); // -1.5707963267948966 (-π/2)
Math.asin(-0); // -0
Math.asin(0); // 0
Math.asin(0.5); // 0.5235987755982989 (π/6)
Math.asin(1); // 1.5707963267948966 (π/2)
Math.asin(2); // NaN
規範
Specification |
---|
ECMAScript® 2025 Language Specification # sec-math.asin |
瀏覽器相容性
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asin |
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- Full support
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