Initial Technical Call

[ywarezk]

Objective

The purpose of the Initial Technical Call is to ask short questions that immediately screen out unqualified candidates. This should help eliminate about 80% of candidates in a 5-minute call, allowing us to increase the volume of developers we interview.

The call can be conducted by HR rather than developers.

During the call, HR will share their screen to display the questions. Neither side should read the questions aloud in order to reduce the chance of AI-generated answers.

The interview will be recorded on video. If there are any doubts about a candidate, the video can be reviewed by one of the developers.

---

Question Topic

The topic of the questions is Promise — something every JavaScript developer should be familiar with.

---

Questions

1. What is wrong with the following code?

   const timerPromise = new Promise((resolve) => {
       setTimeout(() => {
           resolve('hello world');
       }, 2000);
   });
   
   function sayHello() {
       const msg = await timerPromise;
       return msg;
   }

---

2. What is wrong with the following code?

   const randPromise = new Promise((resolve) => {
       setTimeout(() => {
           resolve(Math.random());
       }, 2000);
   });
   
   async function getRandomNumber() {
       const num = await randPromise;
       return num;
   }
   
   const randNum = getRandomNumber();
   console.log(`The random number is: ${randNum}`);

---

3. What is the return type of the following function?

   async function getNum() {
       return 10;
   }

---

4. In the following Express server:

   • A request is sent to the /wait path
   • Then a request is sent to the /rand path

   How long will it take until Node.js starts processing the /rand request?

   import createExpressApplication from 'express';
   
   async function waitTenSeconds() {
       const timerPromise = new Promise((resolve) => {
           setTimeout(() => {
               resolve('It takes 10 seconds for this promise to be resolved');
           }, 10000);
       });
       await timerPromise;
   }
   
   const app = createExpressApplication();
   
   app.get('/rand', (req, res) => {
       res.send(Math.random());
   });
   
   app.get('/wait', async (req, res) => {
       await waitTenSeconds();
       res.send('Finished waiting...');
   });
   
   app.listen(3000, () => {
       console.log('Server is listening on port 3000');
   });

5. What is Promise?