Math.pow()

Math.pow() 静态方法返回基数的幂值。那是

¥The Math.pow() static method returns the value of a base raised to a power. That is

𝙼𝚊𝚝𝚑.𝚙𝚘𝚠 ( 𝚡 , 𝚢 ) = x y \mathtt{\operatorname{Math.pow}(x, y)} = x^y

Try it

语法

¥Syntax

js
Math.pow(base, exponent)

参数

¥Parameters

base

基数。

exponent

指数数。

返回值

¥Return value

代表 base 的 exponent 次方的数字。在以下情况之一返回 NaN：

¥A number representing base taken to the power of exponent. Returns NaN in one of the following cases:

  • exponent 是 NaN。
  • base 是 NaN，exponent 不是 0。
  • base 为±1，exponent 为±Infinity。
  • base < 0 和 exponent 不是整数。

描述

¥Description

Math.pow() 相当于 ** 运算符，只不过 Math.pow() 只接受数字。

¥Math.pow() is equivalent to the ** operator, except Math.pow() only accepts numbers.

Math.pow(NaN, 0)（以及等效的 NaN ** 0）是 NaN 不通过数学运算传播的唯一情况 - 尽管操作数是 NaN，它仍返回 1。此外，base 为 1 且 exponent 为非有限（±Infinity 或 NaN）的行为与 IEEE 754 不同，IEEE 754 指定结果应为 1，而 JavaScript 返回 NaN 以保持与其原始行为的向后兼容性。

¥Math.pow(NaN, 0) (and the equivalent NaN ** 0) is the only case where NaN doesn't propagate through mathematical operations — it returns 1 despite the operand being NaN. In addition, the behavior where base is 1 and exponent is non-finite (±Infinity or NaN) is different from IEEE 754, which specifies that the result should be 1, whereas JavaScript returns NaN to preserve backward compatibility with its original behavior.

因为 pow() 是 Math 的静态方法，所以将其用作 Math.pow()，而不是用作你创建的 Math 对象的方法（Math 不是构造函数）。

¥Because pow() is a static method of Math, use it as Math.pow(), rather than as a method of a Math object you created (Math is not a constructor).

示例

¥Examples

使用 Math.pow()

¥Using Math.pow()

js
// Simple cases
Math.pow(7, 2); // 49
Math.pow(7, 3); // 343
Math.pow(2, 10); // 1024

// Fractional exponents
Math.pow(4, 0.5); // 2 (square root of 4)
Math.pow(8, 1 / 3); // 2 (cube root of 8)
Math.pow(2, 0.5); // 1.4142135623730951 (square root of 2)
Math.pow(2, 1 / 3); // 1.2599210498948732 (cube root of 2)

// Signed exponents
Math.pow(7, -2); // 0.02040816326530612 (1/49)
Math.pow(8, -1 / 3); // 0.5

// Signed bases
Math.pow(-7, 2); // 49 (squares are positive)
Math.pow(-7, 3); // -343 (cubes can be negative)
Math.pow(-7, 0.5); // NaN (negative numbers don't have a real square root)
// Due to "even" and "odd" roots laying close to each other,
// and limits in the floating number precision,
// negative bases with fractional exponents always return NaN,
// even when the mathematical result is real
Math.pow(-7, 1 / 3); // NaN

// Zero and infinity
Math.pow(0, 0); // 1 (anything ** ±0 is 1)
Math.pow(Infinity, 0.1); // Infinity (positive exponent)
Math.pow(Infinity, -1); // 0 (negative exponent)
Math.pow(-Infinity, 1); // -Infinity (positive odd integer exponent)
Math.pow(-Infinity, 1.5); // Infinity (positive exponent)
Math.pow(-Infinity, -1); // -0 (negative odd integer exponent)
Math.pow(-Infinity, -1.5); // 0 (negative exponent)
Math.pow(0, 1); // 0 (positive exponent)
Math.pow(0, -1); // Infinity (negative exponent)
Math.pow(-0, 1); // -0 (positive odd integer exponent)
Math.pow(-0, 1.5); // 0 (positive exponent)
Math.pow(-0, -1); // -Infinity (negative odd integer exponent)
Math.pow(-0, -1.5); // Infinity (negative exponent)
Math.pow(0.9, Infinity); // 0
Math.pow(1, Infinity); // NaN
Math.pow(1.1, Infinity); // Infinity
Math.pow(0.9, -Infinity); // Infinity
Math.pow(1, -Infinity); // NaN
Math.pow(1.1, -Infinity); // 0

// NaN: only Math.pow(NaN, 0) does not result in NaN
Math.pow(NaN, 0); // 1
Math.pow(NaN, 1); // NaN
Math.pow(1, NaN); // NaN

规范

Specification
ECMAScript Language Specification
# sec-math.pow

¥Specifications

浏览器兼容性

BCD tables only load in the browser

¥Browser compatibility

也可以看看

¥See also