查找在Javascript中比较2个数组元素缺失 [英] Find missing element by comparing 2 arrays in Javascript

问题描述

出于某种原因，我有包装我的脑海里解决这个问题的一些严重的困难。我需要接受2个数组，比较2，然后返回缺少元素的字符串这个JS功能。例如。发现在这是出现在previous数组中的currentArray缺少的元素。

For some reason I'm having some serious difficulty wrapping my mind around this problem. I need this JS function that accepts 2 arrays, compares the 2, and then returns a string of the missing element. E.g. Find the element that is missing in the currentArray that was there in the previous array.

function findDeselectedItem(CurrentArray, PreviousArray){

var CurrentArrSize = CurrentArray.length;
var PrevousArrSize = PreviousArray.length;

// Then my brain gives up on me...
// I assume you have to use for-loops, but how do you compare them??

return missingElement;

}

感谢提前！我不要求为code，但哪怕只是在正确的方向上推或暗示可以帮助...

Thank in advance! I'm not asking for code, but even just a push in the right direction or a hint might help...

推荐答案

这应该工作。你也应该考虑其中数组的元素实际上的情况太阵列。如预期那么的indexOf可能无法正常工作。

This should work. You should also consider the case where the elements of the arrays are actually arrays too. The indexOf might not work as expected then.

function findDeselectedItem(CurrentArray, PreviousArray) {

   var CurrentArrSize = CurrentArray.length;
   var PreviousArrSize = PreviousArray.length;

   // loop through previous array
   for(var j = 0; j < PreviousArrSize; j++) {

      // look for same thing in new array
      if (CurrentArray.indexOf(PreviousArray[j]) == -1)
         return PreviousArray[j];

   }

   return null;

}

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