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The JavaScript Interview Handbook: 100+ Interview Questions

Solution Review: Promises

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(){
  return new Promise(function(resolve,reject){
    setTimeout(function(){
      resolve("Func1")
    },1000)
  })
}
function func2(){
  return new Promise(function(resolve,reject){
    setTimeout(function(){
      resolve("Func2")
    },2000)
  })
}
func1()
  .then(func2())
  .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.

Node.js
function func1(){
  return new Promise(function(resolve,reject){
    setTimeout(function(){
      resolve("Func1")
    },1000)
  })
}
function func2(){
  return new Promise(function(resolve,reject){
    setTimeout(function(){
      resolve("Func2")
    },2000)
  })
}
func1()
  .then(func2())
  .then(function(result) {
    console.log(result);
  });

As you can see, the correct option is C. Let’s discuss the code to understand the answer.

On line 18, the func1 function executes, and according to its definition on lines 1-7, it returns a promise. ...