Math.expm1()

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!

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

  1. JavaScript 标准库
  2. Math
  3. 属性
    1. Math.E
    2. Math.LN10
    3. Math.LN2
    4. Math.LOG10E
    5. Math.LOG2E
    6. Math.PI
    7. Math.SQRT1_2
    8. Math.SQRT2
  4. 方法
    1. Math.abs()
    2. Math.acos()
    3. Math.acosh()
    4. Math.asin()
    5. Math.asinh()
    6. Math.atan()
    7. Math.atan2()
    8. Math.atanh()
    9. Math.cbrt()
    10. Math.ceil()
    11. Math.clz32()
    12. Math.cos()
    13. Math.cosh()
    14. Math.exp()
    15. Math.expm1()
    16. Math.floor()
    17. Math.fround()
    18. Math.hypot()
    19. Math.imul()
    20. Math.log()
    21. Math.log10()
    22. Math.log1p()
    23. Math.log2()
    24. Math.max()
    25. Math.min()
    26. Math.pow()
    27. Math.random()
    28. Math.round()
    29. Math.sign()
    30. Math.sin()
    31. Math.sinh()
    32. Math.sqrt()
    33. Math.tan()
    34. Math.tanh()
    35. Math.trunc()
  5. 继承
  6. Object
  7. 属性
    1. Object.prototype.__count__
    2. Object.prototype.__noSuchMethod__
    3. Object.prototype.__parent__
    4. Object.prototype.__proto__
    5. Object.prototype.constructor
  8. 方法
    1. Object.prototype.__defineGetter__()
    2. Object.prototype.__defineSetter__()
    3. Object.prototype.__lookupGetter__()
    4. Object.prototype.__lookupSetter__()
    5. Object.prototype.hasOwnProperty()
    6. Object.prototype.isPrototypeOf()
    7. Object.prototype.propertyIsEnumerable()
    8. Object.prototype.toLocaleString()
    9. Object.prototype.toSource()
    10. Object.prototype.toString()
    11. Object.prototype.unwatch()
    12. Object.prototype.valueOf()
    13. Object.prototype.watch()
    14. Object.setPrototypeOf()