Math.expm1() - JavaScript 编辑

概述

Math.expm1() 函数返回 Ex - 1, 其中 x 是该函数的参数, E 是自然对数的底数 2.718281828459045.

语法

Math.expm1(x)

参数

x

任意数字.

描述

参数 x 会被自动类型转换成 number 类型.

expm1 是 "exponent minus 1" 的缩写.

示例

Math.expm1(1)     // 1.7182818284590453
Math.expm1(-38)   // -1
Math.expm1("-38") // -1
Math.expm1("foo") // NaN

Polyfill

因为我们已经有了 Math.exp函数, 所以很容易 polyfill.

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

规范

Specification	Status	Comment
ECMAScript 2015 (6th Edition, ECMA-262) Math.expm1	Standard	Initial definition.

浏览器兼容性

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

• Desktop
• Mobile

Feature	Chrome	Firefox (Gecko)	Internet Explorer	Opera	Safari
Basic support	未实现	25 (25)	未实现	未实现	未实现

Feature	Android	Chrome for Android	Firefox Mobile (Gecko)	IE Mobile	Opera Mobile	Safari Mobile
Basic support	未实现	未实现	25.0 (25)	未实现	未实现	未实现

相关链接

• Math 对象.