如何对数组中的整数求平方？答案

【问题标题】：How to square integers inside an array?如何对数组中的整数求平方？
【发布时间】：2019-12-15 11:11:19
【问题描述】：

我刚刚过滤了一组小数和整数，所以我只有一组整数。现在我必须计算那些过滤后的整数的平方。

const realNumberArray = [4, 5.6, -9.8, 3.14, 42, 6, 8.34, -2];

const squareList = (arr) => {

"use strict";


  const squaredIntegers = realNumberArray.filter(x => x > 0 && Number.isInteger(x));



return squaredIntegers;
};

// test your code

const squaredIntegers = squareList(realNumberArray);

console.log(squaredIntegers);

【问题讨论】：

可以映射数组 some_array.map(e => e * e)
问题出在哪里？

标签： javascript ecmascript-6

【解决方案1】：

只需映射数组并执行Math.pow(int,power)，但乘法更快，.map 函数中的value * value 也是如此

const realNumberArray = [4, 5.6, -9.8, 3.14, 42, 6, 8.34, -2]; // your array
const squares = realNumberArray.filter(x => x > 0 && Number.isInteger(x)); // your filter function
const squared = squares.map(val => val*val) // map and do val*val to get an array of elements of val*val
console.log(squared) // log it

你的代码变成了

const realNumberArray = [4, 5.6, -9.8, 3.14, 42, 6, 8.34, -2];

const squareList = (arr) => {

  "use strict";
  const squaredIntegers = realNumberArray.filter(x => x > 0 && Number.isInteger(x));
  const squared = squaredIntegers.map(val => val*val)
  return squared;
};

// test your code

const squaredIntegers = squareList(realNumberArray);

console.log(squaredIntegers);

【讨论】：

【解决方案2】：

你可以使用 Array.map

const realNumberArray = [4, 5.6, -9.8, 3.14, 42, 6, 8.34, -2];

const squareList = (arr) => {
    return realNumberArray
        .filter(x => x > 0 && Number.isInteger(x))
        .map(x => x * x);
};

const squaredIntegers = squareList(realNumberArray);

console.log(squaredIntegers);

【讨论】：