Javascript 如何在javascript中从另一个数组中减去一个数组
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How to subtract one array from another in javascript
提问by rrbest
If i have an array A = [1, 4, 3, 2]and B = [0, 2, 1, 2]I want to return a new array (A - B) with values [0, 2, 2, 0]. What is the most efficient approach to do this in javascript?
如果我有一个数组A = [1, 4, 3, 2]并且B = [0, 2, 1, 2]我想返回一个带有 values 的新数组（A - B）[0, 2, 2, 0]。在 javascript 中执行此操作的最有效方法是什么？
回答by Andrii Gordiichuk
const A = [1, 4, 3, 2]
const B = [0, 2, 1, 2]
console.log(A.filter(n => !B.includes(n)))回答by brk
Use mapmethod The map method takes three parameters in it's callback function like below
使用map方法 map 方法在它的回调函数中接受三个参数，如下所示
currentValue, index, array
var a = [1, 4, 3, 2],
b = [0, 2, 1, 2]
var x = a.map(function(item, index) {
// In this case item correspond to currentValue of array a,
// using index to get value from array b
return item - b[index];
})
console.log(x);回答by Sankar
ForSimple and efficient ever.
For简单而高效。
Check here : JsPref - For Vs Map Vs forEach
检查这里： JsPref - For Vs Map Vs forEach
var a = [1, 4, 3, 2],
b = [0, 2, 1, 2],
x = [];
for(var i = 0;i<=b.length-1;i++)
x.push(a[i] - b[i]);
console.log(x);回答by Kamil Mikosz
If you want to override values in the first table you can simply use forEach method for arrays forEach. ForEach method takes the same parameter as map method (element, index, array). It's similar with the previous answer with map keyword but here we are not returning the value but assign value by own.
如果您想覆盖第一个表中的值，您可以简单地将 forEach 方法用于数组forEach。ForEach 方法采用与 map 方法相同的参数（元素、索引、数组）。它与之前使用 map 关键字的答案类似，但在这里我们不是返回值而是自己分配值。
var a = [1, 4, 3, 2],
b = [0, 2, 1, 2]
a.forEach(function(item, index, arr) {
// item - current value in the loop
// index - index for this value in the array
// arr - reference to analyzed array
arr[index] = item - b[index];
})
//in this case we override values in first array
console.log(a);