JavaScript convert a number to a letter of the alphabet | Example code

If want to convert a number to its corresponding alphabet letter like this:-

1 = A
2 = B
3 = C

You will need to write a loop, and mod (%) the number by 26 each time through and use the following:

String.fromCharCode(num + 64);

Convert number to a letter of the alphabet JavaScript example

HTML example code:

Simply do this without arrays using String.fromCharCode(code) function as letters have consecutive codes. For example: String.fromCharCode(1+64) gives you ‘A’, String.fromCharCode(2+64) gives you ‘B’, and so on

<!DOCTYPE html>
<html>
<body>

  <script>

    function getLetter(num){
      var letter = String.fromCharCode(num + 64);
      return letter;
    }

    console.log(getLetter(1));
    console.log(getLetter(2));
    console.log(getLetter(26));
  </script>
</body>
</html>

Output:

JavaScript convert a number to a letter of the alphabet

Another example with a different method

<script>
    var value = 1;
    document.write((value + 9).toString(36).toUpperCase());
</script>

One more example

const toAlpha = (num) => {
   if(num < 1 || num > 26 || typeof num !== 'number'){
      return -1;
   }
   const leveller = 64;
   //since actually A is represented by 65 and we want to represent it
   with one
   return String.fromCharCode(num + leveller);
};
console.log(toAlpha(18));

Q: How to Convert numbers to letters beyond the 26 character alphabet?

Answer: Generate a number as a letter.

<!DOCTYPE html>
<html>
<body>

  <script>

   function colName(n) {
    var ordA = 'a'.charCodeAt(0);
    var ordZ = 'z'.charCodeAt(0);
    var len = ordZ - ordA + 1;

    var s = "";
    while(n >= 0) {
      s = String.fromCharCode(n % len + ordA) + s;
      n = Math.floor(n / len) - 1;
    }
    return s;
  }

  document.write(colName(27));
</script>
</body>
</html>

Output: ab

Do comment if you have any doubts and suggestions on this JS Code.

Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.

OS: Windows 10

Code: HTML 5 Version


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