Finding the immediate next character to a letter in string using JavaScript

Problem

We are required to write a JavaScript function that takes in a string of characters, str, and a single character, char.

Our function should construct a new string that contains the immediate next character present in str after each instance of char (if any).

Example

Following is the code −

 Live Demo

const str = 'this is a string'; const letter = 'i'; const findNextString = (str = '', letter = '') => {    let res = '';    for(let i = 0; i < str.length; i++){       const el = str[i];       const next = str[i + 1];       if(letter === el && next){          res += next;       };    };    return res; }; console.log(findNextString(str, letter));

Output

ssn