Math.pow()

Math.pow() 函式回傳 baseexponent 次方(幂)值,也就是 baseexponent

語法

Math.pow(base, exponent)

參數

base
基數。
exponent
要乘上 base 幾次的指數。

回傳值

A number representing the given base taken to the power of the given exponent.

敘述

The Math.pow() function returns the base to the exponent power, that is, baseexponent, the base and the exponent are in decimal numeral system.

由於 pow()Math 的靜態方法,you always use it as Math.pow(), rather than as a method of a Math object you created(Math 並沒有建構子)。

示例

使用 Math.pow()

// simple
Math.pow(7, 2);    // 49
Math.pow(7, 3);    // 343
Math.pow(2, 10);   // 1024
// fractional exponents
Math.pow(4, 0.5);  // 2 (4 的平方根)
Math.pow(8, 1/3);  // 2 (8 的立方根)
Math.pow(2, 0.5);  // 1.4142135623730951 (2 的平方根)
Math.pow(2, 1/3);  // 1.2599210498948732 (2 的立方根)
// signed exponents
Math.pow(7, -2);   // 0.02040816326530612 (1/49)
Math.pow(8, -1/3); // 0.5
// signed bases
Math.pow(-7, 2);   // 49 (負負得正,2次方都是正數)
Math.pow(-7, 3);   // -343 (3次方有可能為負數)
Math.pow(-7, 0.5); // NaN (負數沒辦法得出一個實數平方根)
// 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
Math.pow(-7, 1/3); // NaN

規範

規範 狀態 註解
ECMAScript 1st Edition (ECMA-262) Standard Initial definition. Implemented in JavaScript 1.0.
ECMAScript 5.1 (ECMA-262)
The definition of 'Math.pow' in that specification.
Standard
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Math.pow' in that specification.
Standard
ECMAScript (ECMA-262)
The definition of 'Math.pow' in that specification.
Living Standard

瀏覽器相容性

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參見