Javascript -- 比较两个数组，返回差异，但是
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Javascript -- Compare two arrays, return differences, BUT
提问by Brad Thomas
I've found a lot of posts that solve this problem:
我找到了很多解决这个问题的帖子：
Assuming we have:
假设我们有：
array1 = ['A', 'B', 'C', 'D', 'E']; array2 = ['C', 'E'];
Is there a proven and fast solution to compare two arrays against each other, returning one array without the values appearing in both arrays (C and E here). Desired solution:
是否有一种行之有效的快速解决方案来比较两个数组，返回一个数组而没有出现在两个数组中的值（此处为 C 和 E）。所需的解决方案：
array3 = ['A', 'B', 'D']
But what if you have:
但是如果你有：
array1 = ['A', 'B', 'C', 'D', 'D', 'E']; array2 = ['D', 'E'];
and you're looking for the solution to be:
并且您正在寻找的解决方案是：
array3 = ['A', 'B', 'C', 'D'] // don't wipe out both D's
Here is some context:
这是一些上下文：
You are trying to teach students about how sentences work. You give them a scrambled sentence:
您正在尝试教学生有关句子的工作原理。你给他们乱七八糟的一句话：
ate -- cat -- mouse -- the -- the
吃——猫——老鼠——————
They start typing an answer: The cat
他们开始输入答案：猫
You would like the prompt to now read:
您希望提示现在阅读：
ate -- mouse - the
吃——老鼠——
At present, my code takes out both the's.
目前，我的代码去掉了两个。
Here is what I've tried:
(zsentence is a copy of xsentence that will get manipulated by the code below, join()ed and put to screen)
这是我尝试过的：
（zsentence 是 xsentence 的副本，它将被下面的代码操纵，加入（）并放到屏幕上）
for (i=0; i < answer_split.length; i++) {
for (j=0; j < xsentence.length; j++) {
(function(){
if (answer_split[i] == xsentence[j]) { zsentence.splice(j,1); return; }
})();
}
}
回答by Matt Ball
Just iterate over the array of elements you want to remove.
只需遍历要删除的元素数组。
var array1 = ['A', 'B', 'C', 'D', 'D', 'E'];
var array2 = ['D', 'E'];
var index;
for (var i=0; i<array2.length; i++) {
index = array1.indexOf(array2[i]);
if (index > -1) {
array1.splice(index, 1);
}
}
It's O(array1.length * array2.length)but for reasonably small arrays and on modern hardware this shouldn't remotely cause an issue.
这是O(array1.length * array2.length)但对于相当小的阵列和在现代硬件上这不应该远程操作，导致的问题。
http://jsfiddle.net/mattball/puz7q/
http://jsfiddle.net/mattball/puz7q/
https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Array/splice
https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Array/splice
回答by Ashish Bhanderi
You can use Filter also. Please review below example.
您也可以使用过滤器。请查看以下示例。
var item = [2,3,4,5];
var oldItems = [2,3,6,8,9];
oldItems = oldItems.filter(n=>!item.includes(n))
so this will return [6,8,9]
所以这将返回 [6,8,9]
and if you want to get only matched items then you have to write below code.
如果您只想获得匹配的项目，则必须编写以下代码。
oldItems = oldItems.filter(n=>item.includes(n))
This will return [2,3] only.
这将仅返回 [2,3]。
