day-1.js

process.stdin.resume();
process.stdin.setEncoding('ascii');

var input_stdin = "";
var input_stdin_array = "";
var input_currentline = 0;

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

process.stdin.on('end', function () {
    input_stdin_array = input_stdin.split("\n");
    main();    
});

// Reads complete line from STDIN
function readLine() {
    return input_stdin_array[input_currentline++];
}

function main() {
    var i = 4
    var d = 4.0
    var s = "HackerRank "
    // Declare second integer, double, and String variables.
    console.log(i + Number(input_stdin_array[0]))
    console.log((d + Number(input_stdin_array[1])).toFixed(1))
    console.log(s + input_stdin_array[2])
}

day-6.js

function splitString(input) {
  const m = ['', '']
  for (let i = 0; input.length > i; i++) {
    if (i % 2 === 0) {
      m[0] += input[i]
    } else {
      m[1] += input[i]
    }
  }
  return m.join(' ')
}

function processData(input) {
  const len = input.splice(0, 1)
  const m = []
  for (let i = 0; len > i; i++) {
    m[i] = splitString(input[i])
  }
  console.log(m.join('\n'))
} 

process.stdin.resume();
process.stdin.setEncoding("ascii");
_input = "";
process.stdin.on("data", function (input) {
    _input += input;
});

process.stdin.on("end", function () {
  processData(_input.split('\n'));
});