JavaScript Background I

Starting Out

In a Windows machine, use CTRL+SHIFT+J to open up the console. This is where we'll practice applying JavaScript
There are 7 primitive types in total: number, string, boolean, undefined, null, symbol, and bigint.
Using the term ** is used for exponentiation: so 2^4 can be expressed as 2**4 in JS. So, 9**2 = 81, 9**3 = 729 etc...
NaN means 'Not a Number'. However, if we run the typeof operator on it, it will still be recognized as a number
To elaborate on the previous point, something like "200 +(0/0)" will evaluate to NaN.

Variables and let

let

In JavaScript, we use:

                        
                            let variableName = value;
                            let numHens = 5;
                            (i.e. so, the number of hens = 5!)

As you can see, using let variableName = value; is how we declare our variables in JavaScript!

Just as in C++, we can use +=, -=, *=, and /=, ++, and -- for variables in JavaScript.

const

The const keyword is similar to using const in C++!

                    
                        const variableName = value;
                        const daysInWeek = 7;

We set variables as constant and don't change them when we use the const keyword!

var

var is the old way of making variables in JavaScript.

It works similarly to let and const, but is considered deprecated.

boolean

As with C++, we can set variables to true/false. Unlike C++, we don't have to name the type of our variable!

let isActive = true; creates a boolean variable, isActive

Interestingly, it is possible to change varaible names in JavaScript.

Name variables well, and use Camel Case to do so...

string

This variable follows many of the same rules as those we see in C++!

One way to find all the functions that you can call upon a string variable is to use the dot operator. Something new is the .trim() function:

                        
                            let bobbyNoSentence = "   Hey, I'm ready to do it!";
                            bobbyNoSentence.trim();
                            //Gives us "Hey, I'm ready to do it!"
                            bobbyNoSentence.trim().toUpperCase();
                            //Gives us "HEY, I'M READY TO DO IT!";

Not the chaining of functions in the above :)