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.

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

∀ x ∊ [ − 1 , 1 ] , 𝙼𝚊𝚝𝚑.𝚊𝚜𝚒𝚗 ( 𝚡 ) = arcsin ( x ) = the unique  y ∊ [ − π 2 , π 2 ]  such that  sin ( y ) = x \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

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Syntax

js
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 - π 2 -\frac{\pi}{2} and π 2 \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()

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

Specifications

Specification
ECMAScript Language Specification
# sec-math.asin

Browser compatibility

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See also