HackerRank Day 2: Conditional Statements: Switch 10 days of javascript solution

In this HackerRank Day 2: Conditional Statements: Switch 10 days of javascript problem you need to Complete the getLetter(s) function in the editor. It has one parameter: a string, S, consisting of lowercase English alphabetic letters

HackerRank Day 2: Conditional Statements: Switch 10 days of javascript problem solution.

'use strict';

process.stdin.resume();
process.stdin.setEncoding('utf-8');

let inputString = '';
let currentLine = 0;

process.stdin.on('data', inputStdin => {
    inputString += inputStdin;
});

process.stdin.on('end', _ => {
    inputString = inputString.trim().split('\n').map(string => {
        return string.trim();
    });
    
    main();    
});

function readLine() {
    return inputString[currentLine++];
}

function getLetter(s) {
    let letter;
    switch (true) {
        case 'aeiou'.includes(s[0]):
            letter = 'A';
            break;
        case 'bcdfg'.includes(s[0]):
            letter = 'B';
            break;
        case 'hjklm'.includes(s[0]):
            letter = 'C';
            break;
        case 'npqrstvwxyz'.includes(s[0]):
            letter = 'D';
            break;
    }
    return letter;
}


function main() {
    const s = readLine();
    
    console.log(getLetter(s));
}