Math.expm1() - JavaScript 编辑

The Math.expm1() function returns ex - 1, where x is the argument, and e the base of the natural logarithms.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

Syntax

Math.expm1(x)

Parameters

x

A number.

Return value

A number representing ex - 1, where 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()

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:

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

Specifications

Specification
ECMAScript (ECMA-262) The definition of 'Math.expm1' in that specification.

Browser compatibility

BCD tables only load in the browser

See also

• Math.E
• Math.exp()
• Math.log()
• Math.log10()
• Math.log1p()
• Math.log2()
• Math.pow()