Read a series of numbers from the terminal, compute their sum when input stream closes

user-input-addition.js

const readline = require('readline');

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  prompt: 'Enter numbers sep by newlines. Ctrl-d when done> \n'
});

let inputStack = [];

// display our prompt with instructions for the user
rl.prompt();

// every time user hits enter, the 'line' event fires
rl.on('line', (input) => {
  // add their input to our stack
  inputStack.push(Number(input));
}).on('close', () => {  // ctrl-d closes the stream, add the numbers, clean up
  console.log('The sum is: ' + inputStack.reduce( (sum,val) => {
    return sum +val;
  }, 0));
  process.exit(0);
})