Math.log2()

概述

Math.log2() 函数返回一个数字以 2 为底的对数.

语法

Math.log2(x)

参数

x
任意数字.

描述

如果传入的参数小于 0, 则返回 NaN.

示例

Math.log2(2)     // 1
Math.log2(1024)  // 10
Math.log2(1)     // 0
Math.log2(0)     // -Infinity
Math.log2(-2)    // NaN
Math.log2("1024")// 10
Math.log2("foo") // NaN

规范

Specification Status Comment
ECMAScript 2015 (6th Edition, ECMA-262)
Math.log2		 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()