Final Exam Deck #2

Question 1

how does the setTimeout( ) function work? What are its parameters?

Answer 1

setTimeout( callback(), msDelay )

It runs the callback function after the indicated delay (ms)

Question 2

What are the parameters of the promise constructor?

Answer 2

resolve and reject

Question 3

What is the “then” method and what does it do? What are its parameter(s)?

Answer 3

“then” is a method of the Promise class. It takes a callback function as a parameter and runs it if the promise is resolved.

Question 4

What is the “catch” method and what does it do? What are its parameter(s)?

Answer 4

“catch” is a method of the Promise class. It takes a callback function as a parameter and runs it if the promise is rejected

Question 5

For the following class:

class Student{

constructor(name, grade){
	this.name = name;
	this.grade = grade;
}

getDetails(){
	return ....
}

static compareGrades(stu1, stu2) {
	....
}

}

Student Shane = new Student(… , …)
Student Cameron = new Student(… , …)

how would you call each of the methods for Shane?

Answer 5

a) Shane.getDetails( );

b) Student.compare(Shane, Cameron);

Question 6

Are static methods class based methods or instance based methods?

Answer 6

Static methods only pertain to the class itself not an instance of the class

Question 7

True or false:

You can call a static method with:

instanceOfClass.staticMethod( )

Answer 7

False:

must be:
ClassName.staticMethod?

Question 8

What does “this” refer to in a static method?

Answer 8

The class itself (as opposed to an instance)

Question 9

For a general use of the reduce method:

const somethingNew = array.reduce( (accumulator, element) =>
, defaultThing);

What value gets assigned to “somethingNew” after reduce has gone through each element of the array?

Answer 9

The accumulator gets assigned to “somethingNew”

i.e. it becomes whatever the accumulator is at the end.

Question 10

Do arrow functions without parentheses have a return statement?

Answer 10

No. The return is implied

Question 10

How is the accumulator value updated each time the callback function runs.

Answer 10

The value returned from the callback function becomes the new accumulator.

Question 10

What is wrong with the following code:

if(raining):
console.log(‘its raining’);
else:
console.log(‘not raining’);

Answer 10

No colon after “if” and “else” statement

Question 11

When using the reduce() method, do we need to declare a base value after the callback function?

Answer 11

Yes

Question 12

Can advanced for loops be used for an object? If so what would it like for nums in a numberArray

Answer 12

Yes

for(const num in NumberArray)

Don’t forget the ‘const’ here

Question 13

When creating a private field of a class, what is the code for the getter and setter methods within the constructor?

Ex: for a private field called “password”

Answer 13

this.getPassword = function(){
return this.__password__;
}

this.setPassword = function(pass){
this.__password__ = pass;
}