# Math.expm1()

The ** Math.expm1()** function returns

`e`^{x} - 1

, where `x`

is the argument, and e the base of the natural logarithms.## Syntax

JavaScript

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Math.expm1(<var>x</var>)

### Parameters

`x`

- A number.

### Return value

A number representing `e`

, where ^{x} - 1`e`

is Euler's number and `x`

is the argument.

## Description

Because `expm1()`

is a static method of `Math`

, you always use it as `Math.expm1()`

, rather than as a method of a `Math`

object you created (`Math`

is not a constructor).

## Examples

### Using `Math.expm1()`

JavaScript

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Math.expm1(-1); // -0.6321205588285577 Math.expm1(0); // 0 Math.expm1(1); // 1.718281828459045

## Polyfill

This can be emulated with the help of the `Math.exp()`

function:

JavaScript

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Math.expm1 = Math.expm1 || function(x) { return Math.exp(x) - 1; };

## Specifications

Specification | Status | Comment |
---|---|---|

ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Math.expm1' in that specification. |
Standard | Initial definition. |

ECMAScript 2017 Draft (ECMA-262) The definition of 'Math.expm1' 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 |

## See also

## License

© 2016 Mozilla Contributors

Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.

https://developer.mozilla.org/en-us/docs/web/javascript/reference/global_objects/math/expm1