Finding the 1-based index of a character in alphabets using JavaScript

Problem

We are required to write a JavaScript function that takes in a lowercase English alphabet character. Our function should return the character’s 1-based index in the alphabets.

Example

Following is the code −

const char = 'j';
const findCharIndex = (char = '') => {
   const legend = ' abcdefghijklmnopqrstuvwxyz';
   if(!char || !legend.includes(char) || char.length !== 1){
      return -1;
   };
   return legend.indexOf(char);
};
console.log(findCharIndex(char));

Output

10