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Javascript – Is there a way to prevent my for loop doubling duplicate letters when comparing two strings for identical letters?

I’ve got an array of strings and a string. Using a for loop, iterating through both the array and the string, I’m hoping to return the letters that are the same in both.

My solution works until there is a duplicate letter in the array. When there is a duplicate, the
relevant letter gets doubled, for example ‘aaa’ would return ‘aaaaaa’.

Below is the code that I have tried most recently.

const fruits = ["Banana", "Orange", "Apple", "Mango", "Apple"];

let myString = "apple";

const fruit = fruits[2].toLowerCase();

for (let i = 0; i < fruit.length; i++) {
  for (let j = 0; j < myString.length; j++) {
    if (myString[j].indexOf(fruit[i]) !== -1) {
      console.log(myString[j]);
      return myString(j)
    }
  }
}
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2

Answers


  1. 0

    You can just check if the whole string matches the fruit,
    then print the letters from that. I got lost in your inner for loops.
    Check this one out:
    https://jsfiddle.net/peu54ry2/

    const fruits = ["Banana", "Orange", "Apple", "Mango", "Apple"];
const myString = "apple";

for (let i = 0; i < fruits.length; i++) {
  if (fruits[i].toLowerCase() == myString) {
    console.log(fruits[i]);
  }
}
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  2. 0

    Assuming you want to look at each word in the array

    You may want to fiddle with the toLowerCases depending on your needs

    const fruits = ["Banana", "Orange", "Apple", "Mango", "Apple"];
let myString = "apple";

const findCommonLetters = (array, string) => {
  const uniqueStringLetters = new Set(string.toLowerCase()); // unique letters in string

  const matches = array.map(fruit => [...new Set(fruit.toLowerCase())]
    .filter(letter => uniqueStringLetters.has(letter)) // find matching letters
    .join(''));
  return matches;
};

console.log(findCommonLetters(fruits, myString));
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