## 概述

`Math.log1p()` 函数返回一个数字加1后的自然对数 (底为 `E`), 既`log(x+1)`.

## 语法

    Math.log1p(x)

### 参数

`x`
  任意数字.

## 描述

如果参数的值小于`-1`, 则返回 `NaN.`

`函数 y = log(x+1) 的图形是这样的:`

示例

    Math.log1p(Math.E-1)  // 1
    Math.log1p(0)         // 0
    Math.log1p("0")       // 0
    Math.log1p(-1)        // -Infinity
    Math.log1p(-2)        // NaN
    Math.log1p("foo")     // NaN

## 规范

Specification | Status | Comment
--- | --- | ---
ECMAScript 2015 (6th Edition, ECMA-262) Math.log1p | 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.