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JavaScript

Posted by Jackson Monk
Jackson Monk
4,527 Points

Don't understand why this doesn't work

I have spent a good 4 hours trying to figure out how to detect what the first repeated character in a string is, and I have code, but my brain is shot. I know it has something to do with the length of charArr, but thinking about all those loops and the length of charArr is overloading my brain. Can someone help me please? Here is my code. I probably overcomplicated it like I usually do.

window.onload = function() {

  let input = document.getElementsByTagName('input')[0];
  let button = document.getElementsByTagName('button')[0];

  let index;
  let characters;
  let splitChar;
  let charArr = [null, null];

  button.addEventListener('click', () => {

    characters = input.value;
    splitChar = characters.split('');
    index = charArr.indexOf(1);

  looping:
     for (let i = 0; i < splitChar.length; i ++) {

       if (i === 0) {

      for (let j = 0; j < charArr.length - 1; j ++) {

        if (splitChar[i] == charArr[j]) {
          document.write('The first repeated character in your sentence was: ' + splitChar[i]);
          break looping;
        }                            
        else {
          charArr.push(splitChar[i]);

          if (splitChar[i + 1] == splitChar.length) {
          document.write('You never had a repeating character!');
          }
        }
        if (j === 0) {
          charArr.splice(index, 1);
        }
      }
     }
       else {

         for (let j = 0; j < charArr.length; j ++) {

        if (splitChar[i] == charArr[j]) {
          document.write('The first repeated character in your sentence was: ' + splitChar[i]);
          break looping;
        }                            
        else {
          charArr.push(splitChar[i]);

          if (splitChar[i + 1] == splitChar.length) {
          document.write('You never had a repeating character!');
          }
        }
        if (j === 0) {
          charArr.splice(index, 1);
        }
      }
       }
    }
});
};

Here is html too:

<html>
<head></head>
  <body>
    <h1>First Recurring Character</h1>
    <h3>Type a series of characters in the box below and the result will be the first character that occurs twice in your sentence</h3>
  <input type = text> <button>Enter</button>
    <script src = floucore.js></script>
  </body>
</html>

Help is appreciated, thanks.

1 Answer

Steven Parker
Steven Parker
243,656 Points
Steven Parker
Steven Parker
243,656 Points

I haven't analyzed your program, but I'll suggest a solution strategy:

The "indexOf()" value of any unique letter will be the same as its position in the string. But the value of a repeated letter will be less than its own position index.