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,
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
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 and , 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® 2026 Language Specification # sec-math.asin |
Browser compatibility
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