The JavaScript Interview Handbook: 100+ Interview Questions/

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Solution Review: Async & Await

Solution Review: Async & Await

In this lesson, we will discuss the solutions to the questions in the previous lesson.

We'll cover the following...

Question 1: Solution review #

In the previous lesson, you were given the following code:

Javascript (babel-node)
function func1(num) {
  return new Promise(function(resolve){
    setTimeout(function(){
      resolve(num);
    }, 1000);
  });
}
async function multiply(num) {
  const x = func1(10);
  const y = func1(3);
  return num * await x * await y;
}
multiply(10).then(function(result){
  console.log(result);
});

For the code above, you had to answer the following question:

Explanation #

Run the code below to see the solution.

Javascript (babel-node)
function func1(num) {
  return new Promise(function(resolve){
    setTimeout(function(){
      resolve(num);
    }, 1000);
  });
}
async function multiply(num) {
  const x = func1(10);
  const y = func1(3);
  return num * await x * await y;
}
multiply(10).then(function(result){
  console.log(result);
});

The code outputs 300, making Option B the correct answer. Let’s understand the code to see why.

On line 15, we call the multiply function with 10 passed as the argument.

async function multiply(num) {
  const x = func1(10); //line 10
  const y = func1(3);
...