javascript 在javascript中对数组中的每个数字进行平方
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Square each number in an array in javascript
提问by dagarre
I'm trying to square each number in an array and my original code didn't work. I looked up another way to do it, but I'd like to know WHY the original code didn't work.
我正在尝试对数组中的每个数字进行平方，但我的原始代码不起作用。我查找了另一种方法来做到这一点，但我想知道为什么原始代码不起作用。
Original code:
原始代码：
function(arr) {
ret= [];
for (var i = 0, len = arr.length; i < len; i++) {
root = Math.sqrt(arr[i]);
ret.push(root);
}
return ret;
}
Working Code:
工作代码：
function(arr) {
ret= [];
for (var i = 0, len = arr.length; i < len; i++) {
ret.push(arr[i] * arr[i]);
}
return ret;
}
回答by Mohsen
Math.sqrtgives you square rootnot square of a number. Use Math.powwith second argument of 2.
Math.sqrt给你平方根而不是数字的平方。Math.pow与 的第二个参数一起使用2。
回答by 1ace
How about that ?
那个怎么样 ？
function (arr) {
return arr.map(function (x) {
return Math.pow(x, 2);
});
}
Array.map(func)applies the function to each element of the map and returns the array composed of the new values.
Math.pow(base, exp)raises baseto its exppower.
Array.map(func)将该函数应用于地图的每个元素并返回由新值组成的数组。
Math.pow(base, exp)提升base到它的exp力量。
回答by John Kraft
The first sample is taking the square root, not squaring the value. To square you want to use
第一个样本是取平方根，而不是对值进行平方。要平方您要使用
Math.pow(arr[i],2);
回答by Penny Liu
回答by BASANT KUMAR
Best way to Square each number in an array in javascript
在javascript中对数组中的每个数字进行平方的最佳方法
Array.prototype.square = function () {
var arr1 = [];
this.map(function (obj) {
arr1.push(obj * obj);
});
return arr1;
}
arr = [1, 6, 7, 9];
console.log(arr.square());
arr1 = [4, 6, 3, 2];
console.log(arr1.square())
回答by TGH
The original code is taking the square root of the value. The second version is multiplying the value with itself (squaring it). These are inverse operations
原始代码是取值的平方根。第二个版本是将值与其自身相乘（平方）。这些是逆运算
回答by Signor Siddarth
Here is how it can be done, using a simple method called .forEach
这是如何做到的，使用一个简单的方法叫做 .forEach
var numbers = [1,2,3,4,5,6,7,8];
numbers.forEach(function(element, index, array){
array[index] = element* element;
});
console.log(numbers);
回答by Abdennour TOUMI
Use embedded for, for pretty syntax :
使用 Embedded for, 以获得漂亮的语法：
var arr=[1,2,3,4] ;
[for (i of arr) i*i ];
//OUT : > [1,4,9,16]
回答by Ad_
let arr = [1, 2, 3];
let mapped = arr.map(x => Math.pow(x, 2));
console.log(mapped);
回答by Mohan Ram
Declarative Programming :)
声明式编程 :)
let list = [1,2,3,4,5,6,7,8,9,10];
let result = list.map(x => x*x);
console.log(result);