How to read variable number of lines from the terminal? - node.js

Question

I need to ask how many inputs the user want to give (one input per line) and read them.
I am trying to keep it as simple as possible without using any libraries or even async. Why? Because I am doing a course on Coursera and I have to upload a JavaScript/Node file as assignment. The one I wrote with async and promise got rejected (for that version look at the end of this post). Somehow input and output is not working with the "Coursera system".
So I am trying to do it without any bells and whistles:
const readline = require('readline');
const rl = readline.createInterface({
input: process.stdin,
terminal: false
});
const r2 = readline.createInterface({
input: process.stdin,
terminal: false
});
let x = null;
let y = [];
rl.on('line', line1 => {
if (line1 !== "\n") {
x = parseInt(line1);
while(x > 0){
r2.on('line', line2 => {
y.push(line2);
});
x -= 1;
}
console.log('You entered these colors:', y);
process.exit();
}
});
Output:
3
You entered these colors: []
Expected output:
[input]3
[input]green
[input]blue
[input]red
[output]You entered these colors: ["green", "blue", "red"]
One that worked but rejected buy Coursera "assignment system":
const readline = require('readline');
const readLineAsync = () => {
const rl = readline.createInterface({
input: process.stdin,
terminal: false
});
return new Promise((resolve) => {
rl.prompt();
rl.on('line', (line) => {
rl.close();
resolve(line);
});
});
};
async function start() {
let line = null;
let colors = [];
line = await readLineAsync();
const numColors = parseInt(line);
for(let count = numColors; count > 0; count--) {
line = await readLineAsync();
colors.push(line);
}
console.log('You entered these colors:', colors);
}
start();

Answer 1

Initially, we want to ask how many colors the user intends to enter. We are sure the input is expected only once so r1.once() is used.
But, the number of times we ask the user for input varies according to the previous input. So we use r1.on() which will not close until terminated. We will use a variable, counter, to ensure the input is asked of the user the required number of times.
const readline = require('readline');
const rl = readline.createInterface({
input: process.stdin,
terminal: false
});
process.stdin.setEncoding('utf8');
rl.once('line', line => {
const count = parseInt(line.toString());
const colors = [];
let counter = 0;
rl.on('line', line => {
const color = readLine(line);
colors.push(color);
if(++counter >= count) {
console.log('You have entered these colros:', colors);
process.exit();
}
});
});
function readLine(line) {
return line.toString();
}
output
3
red
green
blue
You have entered these colros: [ 'red', 'green', 'blue' ]