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.

See full compatibility

The Math.asin() static method returns the inverse sine (in radians) of a number. That is,

\forall x \in [{-1}, 1],\;\mathtt{\operatorname{Math.asin}(x)} = \arcsin(x) = \text{the unique } y \in \left[-\frac{\pi}{2}, \frac{\pi}{2}\right] \text{ such that } \sin(y) = x

Try it

// 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

Syntax

Math.asin(x)

Parameters

x: A number between -1 and 1, inclusive, representing the angle's sine value.

Return value

The inverse sine (angle in radians between $-\frac{\pi}{2}$ and $\frac{\pi}{2}$ , inclusive) of x. If x is less than -1 or greater than 1, returns NaN.

Description

Because asin() is a static method of Math, you always use it as Math.asin(), rather than as a method of a Math object you created (Math is not a constructor).

Examples

Using Math.asin()

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

Specifications

Specification
ECMAScript® 2027 Language Specification # sec-math.asin

Browser compatibility

	desktop					mobile							server
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on iOS	Samsung Internet	WebView Android	WebView on iOS	Bun	Deno	Node.js
`asin`	Chrome – Full support Chrome 1 (Release date: 2008-12-11) footnote Full support	Edge – Full support Edge 12 (Release date: 2015-07-29) footnote Full support	Firefox – Full support Firefox 1 (Release date: 2004-11-09) footnote Full support	Opera – Full support Opera 3 (Release date: 1997-12-01) footnote Full support	Safari – Full support Safari 1 (Release date: 2003-06-23) footnote Full support	Chrome Android – Full support Chrome Android 18 (Release date: 2012-06-27) footnote Full support	Firefox for Android – Full support Firefox for Android 4 (Release date: 2011-03-29) footnote Full support	Opera Android – Full support Opera Android 10.1 (Release date: 2010-11-09) footnote Full support	Safari on iOS – Full support Safari on iOS 1 (Release date: 2007-06-29) footnote Full support	Samsung Internet – Full support Samsung Internet 1 (Release date: 2013-04-27) footnote Full support	WebView Android – Full support WebView Android 4.4 (Release date: 2013-12-09) footnote Full support	WebView on iOS – Full support WebView on iOS 1 (Release date: 2007-06-29) footnote Full support	Bun – Full support Bun 1 (Release date: 2023-09-08) footnote Full support	Deno – Full support Deno 1 (Release date: 2020-05-13) footnote Full support	Node.js – Full support Node.js 0.10 (Release date: 2013-03-11) footnote Full support

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Full support: Full support

Math.asin()

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