Intro to JavaScript

1. Which keywords are used to declare a variable in JavaScript?

You can use let, var, and const. Var is outdated and global, while const and let are local.

2. What is the definition of a function?

A function is a block of code that is put under one tag. So whenever the tag is called, the whole block is call.

3. What are the SOLID principles?

The first one is Single Responsibility. It means that a class should only do one thing. The second one is Open for Extension, closed for modification. This means you should be able to easily add stuff, but not easily change pre-existing stuff. The third one is Liskov Subsitution. That means that a class and a subclass should be decently interchangable. The fourth one is Interface Segregation. This one is that interfaces should be broken up into smaller pieces so that they can be more accurately defined and coded. The last one is Dependency Inversion.

4. Given this array:

let fruit = ['apple', 'banana', 'pineapple',  'orange', 'strawberry']

What index is the pineapple's current position? How do you know?

banana's position is 1. I know this since it starts at 0.

5. With these two objects:

let you = { name:"You", hair: true, friends: [] }
let them = { name:"Them", hair: false, friends: [] }

how would you .push the them object into the you object's array of friends?

You would do them.push(you). This should push them into you, which sounds weird.

6. Give an example of a JavaScript Conditional:

if(x=3){
  x++
}else(x=3)
This function checks if x is = to three. If it is, it increases x by one. If x is not, it sets x equal to 3. 

7. In the for loop below, what is the name of the piece belongs inside the empty "______" space? What would you put here to increase i by one on every iteration?

for ( let i = 0; i < arr.length; _______ ) {
  //...

That is the final expression. You would put i++.

8. What does the DOM acronym stand for? Which file is first accessed to render the DOM?

The DOM is the Document Object Model. The DOM first accesses the HTML file

9. What are the 9 ECMAScript types as defined by MDN?

They are Boolean, Null, Undefined, String, Number, Object, Symbol, BigInt, and Properties. I couldn't find a direct answer, but I pieced together what I found.

10. When it comes to functions or methods, what is the difference between a parameter and an argument?

The parameter is the variable you put in. The arguement is what gets put into the code and run.

11. What is the difference between a primitive value and a reference value?

A primitive value stores the actual value, while a reference value stores where the value is located.