如何比较javascript中的两个arrays，去掉相似值？

Question

I'm new to javascript and web development.

I am planning to compare two Strings and remove the same elements from the said strings.

for example:

str1 = "john" str2 = "jane"

str1 and str2 both have "j" and "n", and therefore removed from the string it's supposed to look like this: str1Res = "oh" str2Res = "ae"

this is my code. the problem is: the firstName variable is correctly processed. However, the secondName doesn't remove anything.

    var firstName = "john"
    var secondName = "jane"
    firstName = firstName.toLowerCase();
    secondName = secondName.toLowerCase();

    //remove whitespaces and split to array
    var firstNameArray = firstName.replaceAll(" ", "").split('');
    var secondNameArray = secondName.replaceAll(" ", "").split('');

    var firstNameRes = [];
    var secondNameRes = [];

    //duplicate array
    firstNameRes = firstNameArray;
    secondNameRes = secondNameArray;

  

    let i, j
   
    //loop the first name
    for (i = 0; i < firstNameArray.length; i++) {
      
      for (j = 0; j < secondNameArray.length; j++) {
        //pair characters of first name with characters from second name
        if (firstNameArray[i] == secondNameArray[j]) {
          //remove the element from the result array
          firstNameRes.splice(i, 1);
        }
      }
    }
    
    //loop the second name
    for (i = 0; i < secondNameArray.length; i++) {
      //pair characters of second name with characters from first name
      for (j = 0; j <firstNameArray.length; j++) {
        //remove the element from the result array
        if (secondNameArray[i] == firstNameArray[j]){
          secondNameRes.splice(i, 1);
        }
      }
    }

output: firstName: 'o','h' secondName: 'j','a','n', 'e' thanks in advance!

Answer 1

You can use regex to do that:

 var firstName = "john" var secondName = "jane" var reg1 = new RegExp("["+firstName+"]","g") var reg2 = new RegExp("["+secondName+"]","g") console.log(firstName.replace(reg2,"")) console.log(secondName.replace(reg1,""))

Answer 2

This is probably too advanced, but you can do this using regular expressions, like this:

var name1 = ...;
var name2 = ...;

var rx = new RegExp('[' + name2 + ']',"g");

name1 = name1.replace(rx,"");

Within regex, the brackets ('[' and ']') turn the string into a collection of characters to match

Answer 3

The problem in your code was you making the duplicated arrays that incorrectly, you need to copy arrays like that:

 var firstName = "john" var secondName = "jane" firstName = firstName.toLowerCase(); secondName = secondName.toLowerCase(); //remove whitespaces and split to array var firstNameArray = firstName.replaceAll(" ", "").split(''); var secondNameArray = secondName.replaceAll(" ", "").split(''); var firstNameRes = [...firstNameArray]; // Here the way we copy the ARRAY elements, it doesn't work like strings. var secondNameRes = [...secondNameArray]; // I CHANGED ALL CODE BELOW FOR YOU TO WORK let indexToRemoveFirstName = []; let indexToRemoveSecondName = []; //loop to get indexes for (let i = 0; i < firstNameArray.length; i++) { for (let j = 0; j < secondNameArray.length; j++) { //pair characters of first name with characters from second name if (firstNameArray[i] == secondNameArray[j]) { //storing the indexes to remove from originals arrays indexToRemoveFirstName.push(i); indexToRemoveSecondName.push(j); } } } //loops to remove from Array after having the indexes, it needs to loop backwards: for (let i = indexToRemoveFirstName.length-1; i >= 0; i--){ firstNameArray.splice(indexToRemoveFirstName[i], 1) } for (let y = indexToRemoveSecondName.length-1; y >= 0;y--){ secondNameArray.splice(indexToRemoveSecondName[y], 1) } console.log(firstNameArray); console.log(secondNameArray);