trouble compreending how to stop the loop if true-CodePudding

it's my first post here and I'm trying to do a freecodecamp exercise.

Here's my code:

function mutation(arr) {
  let newArr = arr[0].toLowerCase();
  let arrNew = arr[1].toLowerCase();
  let test = newArr.split(' ');
  let newTest = arrNew.split(' ');

  for (let i=0; i < test.length; i  ) {
    for (let j=0; j < newTest.length; j  ) {
      if (newTest[j] === test[i]) {
        return true;
      }
    }
  }
  return false;
}

mutation(["hello", "hey"]);

The exercise is "Mutations" and I need to return true if the 1st string on the array has all the letters from the 2nd. I'm trying to understand how to stop the loop when the if statement is true and save it.

Thanks in advance and sorry if I didn't explain myself correctly.

CodePudding user response：

The following code should help you.

function mutation(arr) {
    let newArr = arr[0].toLowerCase();
    let arrNew = arr[1].toLowerCase();
  
    for (let i=0; i < newArr.length; i  ) {
        if (arrNew.indexOf(newArr[i]) == -1) {
            return false;
        }
    }
    return true;
}

mutation(["hello", "hey"]);

There is no need to use arrays. in JS, strings work like arrays and we can use a "for" loop.

CodePudding user response：

For your question

return will exit the function and therefore will exit the loop.
From that we know that if your function returns false the condition newTest[j] === test[i] was never verified.

Hint for the exercise

You can suppose that the first word has all the letters from the second, iterate just like you're doing right now and check if you find a counter-example !

CodePudding user response：

If you want to utilize loops like in your example code here is a very verbose way to do so:

function mutation(arr) {
  let hasAllLetters = true;
  let stringToCompare = arr[0].toLowerCase();
  let referenceString = arr[1].toLowerCase();
  let hasCurrentLetter;
  
  for (let i=0; i < referenceString.length; i  ) {
    hasCurrentLetter = false;
    
    for (let j=0; j < stringToCompare.length; j  ) {
        
      if (referenceString[i] === stringToCompare[j]) {
        hasCurrentLetter = true;
        
        // break from the second loop as soon as the condition is satisfied
        break;
      }
    }
        
    if(!hasCurrentLetter){
      hasAllLetters = false;
      // as soon as there is at least one letter which does not exist from the reference string
      // break from the second loop and exit yielding the result false
      break;
    }
  }
  
  return hasAllLetters;
}

let res;

res = mutation(["hello", "goll"]);
console.log("res: ", res); // false

res = mutation(["hello", "olhh"]);
console.log("res: ", res); // true