# Math.asinh()

The Math.asinh() function returns the hyperbolic arcsine of a number, that is

$Math.asinh(x)=arsinh(x)= the unique ysuch thatsinh(y)=x\mathtt{\operatorname{Math.asinh}(x)} = \operatorname{arsinh}(x) = \text{ the unique } \; y \; \text{such that} \; \sinh(y) = x$

## Syntax

JavaScript
Math.asinh(<var>x</var>)

### Parameters

x
A number.

### Return value

The hyperbolic arcsine of the given number.

## Description

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

## Examples

### Using Math.asinh()

JavaScript
Math.asinh(1);  // 0.881373587019543
Math.asinh(0);  // 0

## Polyfill

We have $\operatorname \left\{arsinh\right\} \left(x\right) = \ln \left\left(x + \sqrt\left\{x^\left\{2\right\} + 1\right\} \right\right)$ and so this can be emulated by the following function:

JavaScript
Math.asinh = Math.asinh || function(x) {
if (x === -Infinity) {
return x;
} else {
return Math.log(x + Math.sqrt(x * x + 1));
}
};

## Specifications

Specification Status Comment
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Math.asinh' in that specification.
Standard Initial definition.
ECMAScript 2017 Draft (ECMA-262)
The definition of 'Math.asinh' in that specification.
Draft

## Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 38 25 (25) No support 25 7.1
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support No support No support 25.0 (25) No support No support 8