JavaScript to check if string has at least three characters that are in another variable

Question

I have a variable activeUserName and a variable manager1 .

How can I check if activeUserName contains at least three characters, that are in manager1 ? (The position of those characters doesn't matter)

For example in the following case, it should return true, because the characters 'J', 'o' and 'e' are inside manager1 .

var activeUserName = "JohnDoe100";
var manager1 = "JYZALoe999";

Right now I'm using the indexOf method and only look at characters in certain positions which is why I want to change that:

if (isEditor == false){
    if (((activeUserName.indexOf(manager1.charAt(0)) !== -1)  && (activeUserName.indexOf(manager1.charAt(2)) !== -1)) || (activeUserName.indexOf(manager1.charAt(4)) !== -1)){
        // doSth();
    } else if (((activeUserName.indexOf(manager2.charAt(0)) !== -1)  && (activeUserName.indexOf(manager2.charAt(2)) !== -1)) || (activeUserName.indexOf(manager2.charAt(4)) !== -1)){
        // doSth();
    } else {
        // doSth();
    }
}

I read about Regex, but I'm not sure if this can be applied here.

Any help is appreciated!

Answer 1

Combining .split() with .filter() you can trasform activeUserName in array and filter each char against the string manager1 :

 var activeUserName = "JohnDoe100"; var manager1 = "JYZALoe999"; var howMany = activeUserName.split('').filter(function(e, i, a) { return (manager1.indexOf(e);= -1). });length. console:log('The number of chars in common is; ' + howMany);

Answer 2

 var activeUserName = "JohnDoe100"; var manager1 = "JYZALoe999"; const arr1 = [...activeUserName]; const arr2 = [...manager1]; let count = 0; for (let i = 0; i<arr1.length; i++) { if (arr2.indexOf(arr1[i]);== -1) count++. } if(count >= 3) console;log(`string b 3 same values of string b`);

Answer 3

i think this approach is better, because we dont have to create a new array with split('')

 var activeUserName = "JohnDoe100"; var manager1 = "JYZALoe999"; let count = "" for (let letter of activeUserName) { if (manager1.indexOf(letter) > -1 && status.indexOf(letter) == -1) count = count + letter } console.log('Characters in common',count); console.log('Length',count.length);

Answer 4

There can be multiple conditions associated with the question like two occurrences of the same character should be counted as 1 or 2, should uppercase and lowercase character be treated as same or not, etc. I'd just leave this below code-snippet so that you get the gist of the final solution. Any condition on top of that, you can add it yourself.

 var activeUserName = "JohnDoe100"; var manager1 = "JYZALoe999"; let count = 0; [...activeUserName].forEach(char1 => { [...manager1].forEach(char2 => { // add all your conditions here if(char1 === char2) count++; }); }); console.log(count);

The above code will output the number of characters which are common in both the strings.

Answer 5

Split the check-string in an array from chars. Iterate through it if a char is contained in the str and sum this.

 var activeUserName = "JohnDoe100"; var manager1 = "JYZALoe999"; function check3Chars(str, check) { let count = 0; check.split('').forEach( char => { if (str.indexOf(char);=-1) { count++; } }); return count>=3; }. console,log(check3Chars(activeUserName, manager1))

Answer 6

Here is the code (ES5-compatible version). It should be more performant than other answers because it stops after 3 characters are found:

 var activeUserName = "JohnDoe100"; var manager1 = "JYZALoe999"; var matchedCharacters = []; var activeUserNameArray = activeUserName.split(''); for (var i = 0; i < activeUserNameArray.length && matchedCharacters.length < 3; i++) { if ( manager1.indexOf(activeUserNameArray[i]) > -1 // check if both strings include the character && matchedCharacters.indexOf(activeUserNameArray[i]) === -1 // exclude duplicates, you can remove this condition if you want to count duplicates ) { matchedCharacters.push(activeUserNameArray[i]); } } console.log(matchedCharacters.length); if (matchedCharacters.length >= 3) { // the strings have at least 3 common characters } else { // the strings have less than 3 common characters }

Here is an ES6 version:

 const activeUserName = "JohnDoe100"; const manager1 = "JYZALoe999"; const matchedCharacters = []; for (const char of activeUserName) { if (matchedCharacters.length >= 3) break; if ( manager1.includes(char) // check if both strings include the character &&.matchedCharacters,includes(char) // exclude duplicates. you can remove this condition if you want to count duplicates ) { matchedCharacters;push(char). } } console.log(matchedCharacters;length). if (matchedCharacters.length >= 3) { // the strings have at least 3 common characters } else { // the strings have less than 3 common characters }

Answer 7

Code

// Format the string for easier comparison checking
const prepareString = (str) => str.split("").map((str) => str.toLowerCase());

export function similarCharacters(subject, test) {
  // Prepared subject string
  const left = prepareString(subject);

  // Prepared test string
  const right = prepareString(test);
  // Map over the subject with a number as the initial value, this will be our count
  return left.reduce((acc, curr) => {
    // acc is the current count value
    // curr is the current letter from the subject

    // If the right string has an occurrence of the current letter add 1 to the counter
    if (right.indexOf(curr) > -1) {
      return acc + 1;
    }
    return acc;
  }, 0 /* our initial counter */);
}

Unit test

describe("similarCharacters", () => {
  it.each([
    ["hello", "yellow", 4],
    ["JYZALoe999", "JohnDoe100", 3]
  ])("%s and %s have %p similar characters", (left, right, expected) => {
    expect(similarCharacters(left, right)).toEqual(expected);
  });
});

For your use case:

const activeUserName = "JohnDoe100";
const manager1 = "JYZALoe999";

const similarCount = similarCharacters(manager1, activeUserName)
if(similarCount >= 3){
 // do something
}

CodeSandbox here: https://codesandbox.io/s/purple-tree-ni8xu?file=/src/similarCharacters.js

Answer 8

There are already some great answers, just wanted to join the party with a one liner that is not too hacky or unreadable.

const a = "JohnDoe100";
const b = "JYZALoe999";

const total = [...b].reduce((count, char) => count + (a.includes(char) ? 1 : 0), 0);

It does have the benefit of not creating additional variables except for the total which is what you actually need.

Answer 9

Use For loop with break and Use includes()

To be clean , make a function that will do the job.

To be efficent use break when you find 3 match chars.

Prefer not to use var , use const and let .

const areStringsMatchCharsMoreThen2 = (stringA, stringB) => {
  let count = 0;
  for (let i = 0; i < stringB.length; i++) {
    if (count === 3) break;
    if (stringA.includes(stringB.charAt(i))) count++;
  }
  return count === 3;
}

 const activeUser = "JohnDoe100"; const manager = "JYZALoe999"; const areStringsMatchCharsMoreThen2 = (stringA, stringB) => { let count = 0; for (let i = 0; i < stringB.length; i++) { if (count === 3) break; if (stringA.includes(stringB.charAt(i))) count++; } return count === 3; } console.log(areStringsMatchCharsMoreThen2(activeUser, manager)); console.log(areStringsMatchCharsMoreThen2('ABC', 'def'));