Due to the Coronavirus (COVID-19) outbreak, I've decided to learn a new skill. I was always interested in computer programming, and I felt like there was no time like the present. So I just started learning JavaScript through TeamTreehouse.com and have decided to make my study notes public. I will be referring here for my notes but I also invite anybody else who's learning JavaScript to have a peek. Wish me luck!
Course: JavaScript Basics Date: Friday, April 3, 2020
Notes:
One of the most in-demand developer skills
The most common place to find JavaScript is on the web
Because it's implemented in a web browser, you don't need any additional files to get started
You can run a script in your browser by opening the console, pasting your script in there and hitting ENTER
prompt is used to receive an input from the user. ie. prompt("What is your name? ")
JavaScript doesn't only run on browsers. Using JavaScript you can build apps and software that can be used by anyone on just about any device.
Variables, Data Types, and Conditional Statements are concepts not only found in JavaScript but other programming languages as well.
alert(); command opens up a dialogue box
alert("Hello World!"); comment opens a dialogue box that displays your alert.
These alerts are examples of a JavaScript Statement - are like sentences. How sentences end with a period, JavaScript sentences end with a semi-colon ;
console.log(); is going to log or print the message you type in the parentheses to the Console.
document.write(); is a command that writes something to the current document. Not the most common way to display content on a webpage, but useful in situations.
One statement needs to complete before the next statement can run.
JavaScript Engine - a program (or interpreter) built into the browser that executes JavaScript code. Browsers all have a JavaScript engine.
To link a JavaScript file (.js) to an HTML file (.html) you use a . This script tag goes inside the of the HTML file.
Information that changes is stored in a VARIABLE
Score in a game is a VARIABLE.
var is short for VARIABLE and it creates a variable. This is what's called Declaring a Variable. For instance, var score = 0;
When you place something in a VARIABLE it's called assigning a value to the variable.
score = score + 10; is the same as score += 10. It's the shorthand method to add to the value of the variable score
const and let alsoworksimilar to var, you can store variables in them. But they have different rules and can make your code less error-prone.
const is short for constant and is the most useful. Once you create a constant and assign it a value, you can't assign it another value. You can't or manipulate it's value.
Use the let keyword when you want to reassign a variable. The let keyword is almost the same as var.
JavaScript doesn't care too much about spaces. You can even spread a single JavaScript statement over multiple lines.
To make a string upper case, concatenate using the .toUpperCase() dot notation. For instance firstName.toUpperCase()
To make a string lower case, concatenate using the .toLowerCase() dot notation. For instance firstName.toLowerCase()
To count the length of a string, use the .length dot notation when concatenating. For instance, fullName.length;
In JavaScript, a string can contain HTML tags like
If something has a () after it, it's called a METHOD. For instance, prompt() is a prompt METHOD.
String Concatenation is the process of combining two strings together to create a bigger string.
"Click the button to generate a quote" -Sepy Bazzazi