Blog 9 - JavaScript pt.1
Intro
In last week’s blog post, I talked about the MEAN/MERN stack. I discussed each of the components and why you might choose a MEAN/MERN stack. Since my group will be using a MERN stack, we’re learning JavaScript together. This week I’ll be talking about JavaScript and some of the basics.
Basics
First of all, what is JavaScript? It’s a programming language, that alongside HTML and CSS, is one of the core technologies of the World Wide Web. JS is able to be run both on the client-side and server-side, with most web browsers being able to run it natively. I should point out that Java and JavaScript, although sharing a part of the name, are two completely different languages. That isn’t to say they don’t share some similarities in things like syntax, however. So, now that we know some more about JS, let’s dive into its data types, how to declare variables, how to print, and other basics.
Printing and Comments
The first thing you have to do in every programming language is “Hello World” right? Well, in JS we act on the console object and use the .log method in order to print to the screen. Comments are the same as Java. You don’t have to end lines with ;, but it’s good to be in the habit of doing so. Take a look at the code block below:
// single-line comment
/* block or
multi-line
comment */
console.log("Hello World");
Data Types
In JS, there are 7 data types: string, number, boolean, null, undefined, symbol, and object. Strings, numbers, boolean, and null types are pretty standard to any programming language and don’t need to be explained. The difference between null and undefined is that a variable will be undefined if it was declared but not given a value. Null, meanwhile, is the absence of value. Symbols are unique identifiers that I won’t explain more about yet. Finally, objects are just collections of data. The first 6 data types are considered primitive data types.
Variables
Since JS is dynamically typed, you don’t have to explicitly declare the data type of the variable. You can declare variables 3 ways, using the keywords: var, let, or const. var was the only general way to declare variables pre-ES6 (version 6 of ECMAScript or ES, another name for JS). let is the newer keyword introduced in ES6 and is often preferred. There are some differences between var and let but I won’t get into it here. To read more about it, visit this link. const is another way to declare a variable, however after declaration you aren’t able to modify the value of that constant variable.
// Examples of variable declaration
const myName = "Monica";
var school = "CSUN";
let gradeLevel = 4;
String Interpolation
Another great feature of ES6 is the ability to use string interpolation. This means we insert, or interpolate, variables into strings using template literals. Take a look at the code below to see it in action:
let favPokemon = "Pikachu";
console.log(`${favPokemon} is my favorite Pokemon. Just too cute!`);
Wrap the template literal in backticks (`) and put a placeholder ${variable} to insert the actual value of the variable into the template literal. String interpolation is great because it makes things more readable!
Next Week
I’ll probably continue JS next week so stay tuned!