JS Course 1: Fundamental 3

Question 1

What are functions useful for?

Answer 1

Functions are useful for achieving a single task without needing to rewrite the code to run a task over and over again.

Question 2

What’s the difference between functions and methods?

Answer 2

Functions are a set of instructions th perform a single task and do not associate with methods.

Methods are like functions, but they specifically only associate with objects.

Question 3

What are function parameters? What are optional parameters and default parameters?

Answer 3

Function parameters, or arguments, are values you apply to a function when invoking them. They are values needed to be included inside the function’s parentheses to do it’s job properly.

Optional parameters are function parameters that are not required for the function to run, but can be applied if needed.

Default parameters are function parameters that have preset/default settings or values (unless they’re reassigned.)

Question 4

What are function arguments?

Answer 4

Function arguments, compared to function parameters, are the actual values passed through a function. Function parameters are the variables or other values to be used in the function, but function arguments are the actual values you pass into a function.

Question 5

How do you invoke a function?

Answer 5

You invoke a function by calling the name in arguments or applying the function to a variable

Examples:
prompt(“You’re stupid”)

or

variable.Boolean()

Question 6

What is function scope?

Answer 6

Function scope refers to the scope of variables that can only be seen inside a function.

Question 7

What is Global Scope?

Answer 7

Global Scope refers to the variables that are retrievable on the outside of functions. In other words, everywhere on the page except for inside functions.

Question 8

What are Local Variables

Answer 8

Local variables are variables inside a function that are inaccessible to the global scope.

Question 9

What are Outer Variables?

Answer 9

Outer variables are variables that can be retrieved by functions outside of those functions, also called Global Variables.

Question 10

What are return values?

Answer 10

Return values are the values returned after running a function.

Question 11

What are anonymous functions?

Answer 11

Anonymous functions are functions that do not have a name. This is done with the syntax of function expression.

Syntax:
(function () {
alert(‘hello’);
})

Question 12

What are arrow functions?

Answer 12

Arrow functions are functions created with an alternative, more compact syntax using the arrow symbol =>.

Question 13

What are custom functions?

Answer 13

Custom functions are functions you can customize in your code. You can customize the job it does and the name of the function.

Question 14

What is function declaration?

Answer 14

Function declaration is a way to create a function.

Syntax:
function myFunction() {
alert(‘hello’);
}

Question 15

What is function expression?

Answer 15

Function expression is a way to create a function.

Syntax:
let sayHi = function() {
alert( “Hello” );
};

Question 16

What is the “return” statement?

Answer 16

A “return” statement contains the information in a functions or action that will be returned. The statement determines the outcome of a function or action.

This statement also indicates that this is the end of any code to be run inside a function or code block. Once a return statement is met, no code after in that block will be run.

Question 17

What are callback functions?

Answer 17

Callback functions are functions that are passed and expected to be called back later if necessary. This concept can be duplicated using function expressions or anonymous functions (which they also tend to have better flow than callback functions.)

Question 18

What are JavaScript Call Stacks?

Answer 18

javaScript Call Stacks is a mechanism to keep track of the function calls and how the JavaScript engine executed what code when.