JavaScript Crash Course

The contents of this course are derived from the JavaScript Crash Course located on The Codevolution YouTube Page.

While this is not a completely exhaustive list, what follows is an extensive list of topics to get beginners going. I found a lot of value in the crash courses when I was first beginning to code and took extensive notes as I followed along. So, in coder fashion, I made websites out of the content and deployed them through Netlify

You can find the GitHub Repo with all of the code Here.

Primitives

• string
• number
• boolean
• undefined
• null
• bigint
• symbol

Non-primitves

objects

Operators

• Assignment
• Arithmetic
• Comparison
• Logical
• String
• Other

Type Conversions

Equality

==

strict ===

Conditional Statements

if else else if switch

Loops

For Loops

for (initializer; condition; final-expression) { //code to run }

ex. for(let i = 1; 1 <=5; i++) { console.log('Iteration number ' + i) }

While Loops

Same execution as For loops

• variable is set
• condition is evaluated
• code is run while the condition is true
• code is terminated once the condition is false

initializer while (condition) { //code to run final-expression }

ex. let i = 1 while(i <=5>){ console.log('Iteration number ' + i) i++ }

Do..While loop

Executes the code block once and then evaluates the condition

initializer do { //code to run final-expression } while (condition)

ex. let i = 6 do { console.log('Iteration number ' + 1) i++ } while(i <=5)

// since 6 is greater than 5, the loop is exectuted once and then terminated

For..of Loop

Used to loop over a collection of data, like looping over an array

for (const item of array) { //code to run }

ex. const numArray = [1,2,3,4,5]

for (const num of numArray){ console.log('Iteration of number ' + num) }

• automatically iterates of array, and in each iteration, assigns the value of the element as num. ie. in the first iteration num = 1, first iteration num = 2, etc...

• best suited for a collection of data since it abstracts away two things.

  • 1. you don't have tp keep track of a variable ot increment the iteration count.

  • 2. you don't have to figure out how to access the item in the collection

Functions

A JavaScript function is a block of code designed to perform a particular task. ie, add two numbers, multiply two numbers, etc...

Functions are reusable as they can be defined once and can be called with different values, resulting in different results

Functions help divide a complex problem into smaller chunks and makes your program easy to understand and maintain

ex. function name (parameter1, parameter2, paramter3) { //code to be executed } name(argument)

ex. function greet(username) { console.log('Good morning ' + username) } greet('Bruce')

ex. function add(a,b){ return a + b } const sum = add(5,10) console.log(sum)

a + b are two input paramters. in the function body, we add the two paramters and return the sum of the two parameters.

Arrow Functions

Give you a more precise syntax

const arrowSum = (a,b) => { return a + b } const sum = arrowSum(25,25) console.log(sum)

// since we just have a single return statement, we can ommit the curly braces and the return statement and inline the return statement on the same line. The new function looks like:

const arrowSum = (a, b) => a + b const sum = arrowSum(25, 25) console.log(sum)

// if you just have one argument, you can ommit the parathesis around the argument

ex. const addFive = num => num + 5

Scope

Scope determines the accessibility or visibility of variables

There are Three types of Scope

1. Block Scope
2. Function Scope
3. Global Scope

Block Scope

Dictates that variables declared inside a set of curly braces cannnot be accessed outside the curly braces

Function Scope

Variables declared inside a function are not accessible from outside the function

Global Scope

The scope outside any block or function. A global scoped variable is accessible both inside a block and inside a function