My app code:
const readline = require('readline');
const rl = readline.createInterface({
input: process.stdin,
output: process.stdout
});
async function init() {
while (true) {
console.log("TICK");
await (rl.question('What do you think of Node.js? ', await (answer) => {
console.log('Thank you for your valuable feedback:', answer);
rl.close();
}))
await new Promise(resolve => setTimeout(resolve, 1000))
}
}
How it must work (or how i think it should work):
When we meet await (rl.question('...
it should wait for the response (user input) and only than loop continue.
How it actually works
When it meets await new Promise(resolve => setTimeout(resolve, 1000))
it's working, but with await (rl.question('...
you get output but code continue executing without waiting for user input.
async
functions require a function that returns a promise. rl.question
doesn't return a promise; it takes a callback. So you can't just stick async
in front of it an hope it will work.
You can make it work by wrapping it in a promise, but this is probably more work than it's worth:
const readline = require('readline');
const rl = readline.createInterface({
input: process.stdin,
output: process.stdout
});
function rl_promise(q) {
return new Promise(resolve => {
rl.question('What do you think of Node.js? ', (answer) => {
resolve('Thank you for your valuable feedback:', answer)
})
})
}
async function init() {
while (true) {
console.log("TICK");
let answer = await rl_promise('What do you think of Node.js? ')
console.log(answer)
}
rl.close();
}
init()
Having said that, a better approach is to avoid the while loop and have a stopping condition. For example, when the user types 'quit'. I think this is simpler and much easier to understand:
const readline = require('readline');
const rl = readline.createInterface({
input: process.stdin,
output: process.stdout
});
function ask() {
rl.question('What do you think of Node.js? ', (answer) => {
console.log('Thank you for your valuable feedback:', answer);
if (answer != 'quit') ask()
else rl.close();
})
}
ask()
While loop is not async. It is needed to use an async function as iteratee. You can find more info here:
https://medium.com/@antonioval/making-array-iteration-easy-when-using-async-await-6315c3225838
Personally I've used Promise.map of bluebird.
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