JavaScript 指数 - 开卷题库

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Math.pow():

js> Math.pow(12, 2)
144

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Math.pow(base, exponent), for starters.

Example:

Math.pow(12, 2)

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Math.pow(x, y) works fine for x^y and even evaluates the expression when y is not an integer. A piece of code not relying on Math.pow but that can only evaluate integer exponents is:

function exp(base, exponent) {
exponent = Math.round(exponent);
if (exponent == 0) {
return 1;
}
if (exponent < 0) {
return 1 / exp(base, -exponent);
}
if (exponent > 0) {
return base * exp(base, exponent - 1)
}
}

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最佳答案

There is an exponentiation operator, which is part of the ES7 final specification. It is supposed to work in a similar manner with python and matlab:

a**b // will rise a to the power b

Now it is already implemented in Edge14, Chrome52, and also it is available with traceur or babel.

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How we perform exponents in JavaScript
According to MDN
The exponentiation operator returns the result of raising the first operand to the power second operand. That is, var1 var2, in the preceding statement, where var1 and var2 are variables. Exponentiation operator is right associative: a ** b ** c is equal to a ** (b ** c).
For example:
2**3 // here 2 will multiply 3 times by 2 and the result will be 8.
4**4 // here 4 will multiply 4 times by 4 and the result will be 256.

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Working Example:

var a = 10;
var b = 4;


console.log("Using Math.pow():", Math.pow(a,b)); // 10x10x10x10
console.log("Using ** operator:", a**b);  // 10x10x10x10

You can use either Math.pow() or ** operator

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Math.pow function is deprecated

Math.pow(a,b)

So better to use the exponentiation assignment ** as:

a**b

Example:

const postMoneyValuationRevenue = Math.round(
exitValueRevenue / (1 + returnRatePercentage / 100) ** exitYear,
);

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// Using Math.pow
console.log(Math.pow(12, 2)); // 144
// Using ES7
console.log(12**2); // 144
// Using Recursion
const power =(base, exponent) => {
if (exponent === 0) return 1;
return base * power(base, exponent - 1);
}
console.log(power(12,2)); // 144