HackerRank TimeConversion Challenge: https://www.hackerrank.com/challenges/time-conversion?isFullScreen=true

timeConversion.js

'use strict';

const fs = require('fs');

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

let inputString = '';
let currentLine = 0;

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

process.stdin.on('end', function() {
    inputString = inputString.split('\n');

    main();
});

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

/*
 * Complete the 'timeConversion' function below.
 *
 * The function is expected to return a STRING.
 * The function accepts STRING s as parameter.
 */

function timeConversion(s) {
    // Write your code here
    let convertedTime = '';
    const timeFormatStatus = s.endsWith('AM');
    const sLength = s.length;
    let sStart = s.slice(0, 2);
    const sEnd = s.slice(2, sLength-2);
    
    if(timeFormatStatus) {
        !(sStart === '12') && (convertedTime = sStart + sEnd);
        (sStart === '12') && (convertedTime = '00'+ sEnd);
    } else {
        let sToInt = '';
        (sStart === '12') && (convertedTime = sStart + sEnd);
        if(!(sStart === '12')) {
           let sToInt = parseInt(sStart)+12;
            convertedTime = sToInt.toString() + sEnd; 
        }
        
    }
    
    return convertedTime;
}

function main() {
    const ws = fs.createWriteStream(process.env.OUTPUT_PATH);

    const s = readLine();

    const result = timeConversion(s);

    ws.write(result + '\n');

    ws.end();
}