How do I get dynamic index position for a specific character for a input text?

Issue

let's assume an input string has given, for a particular character like '$' you want to add dynamically in the text field , so I want to find the index of a current character like '$' then it's not working properly like initially if I give '$'in any position, its reflection the position, example if I give 'random text$' it returns index 11 but if you type '$'in between text like 'random $text$' then it should return 7, but it returns 12,so by achieving 7 I need to give extra space like 'random $ text$', so dynamically how to get the index position of a current character($), whether It's added in first, middle, last of the text

  let string = "random $text$";
  let newArray = string.split("");
  let store = string.length % 2 !== 0
    ? newArray.findLastIndex((x) => x === "$")
    : newArray.findIndex((x) => x === "$");

  console.log(store);

Solution

As you just want to add a space after first occurance of $ in the input string. You can simply achieve that by using String.replace() method instead of looking for index as If pattern in replace function is a string, only the first occurrence will be replaced. The original string is left unchanged.

Live Demo :

function checkIndex(e) {
  const val = e.target.value;
  console.log(val.replace('$', '$ '));
}

<input type="text" id="val" onBlur="checkIndex(event)"/>

Update : Here is the workaround solution but not a good practice to do. For demo, I am using an input and after getting the index, I am replacing the $ with some other character so that I can get the index of current/newly added $.

Demo :

function checkIndex(e) {
  const val = e.target.value;
  if (/$/.test(val)) {
    console.log(val.indexOf('$'))
    document.getElementById('val').value = val.replaceAll('$', '-')
  }
}

<input type="text" id="val" onBlur="checkIndex(event)"/>

Answered By - Rohìt Jíndal