Highlights of JavaScript — Variables, Switch, and While Loops

To learn JavaScript, we must learn the basics.

To learn JavaScript, we must learn the basics.

In this article, we’ll look at the most basic parts of the JavaScript language.

Local vs Global Variables

JavaScript has local and global variables.

Local variables are accessible only within a block.

And global variables are available throughout the app.

With JavaScript, we create local variables with the let and const keywords.

They are all block-level, so they’re all only available within a block like functions, and if blocks.

let creates a variable, and const creates constants.

Constants can’t be reassigned a new after it’s assigned a value.

But the content may still change.

Constants must have an initial value assigned to it when it’s created.

For example, if we have:

function addNumbers() {
  let theSum = 2 + 2;
}

The theSum is only available within the addNumbers function.

But if we have:

function addNumbers() {
  theSum = 2 + 2;
}

then theSum is a global variable.

We can access the value anywhere.

If a variable is global, then it’s attached property of the window global object.

We should avoid global variables since it’s easy to create global variables with the same name.

Therefore, it’s easy to have conflicts.

And it’s hard to track how variables are changed.

javascript technology programming

Exercise from Eloquent JavaScript. Today, we will write a function that forms a chessboard. You can find the exercise in the Eloquent Javascript book (3rd edition, chapter 2; Program Structure). Write a program that creates a string that represents an 8×8 grid, using newline characters to separate lines. At each position of the grid there is either a space or a “#” character. The characters should form a chessboard.

One of the nice things about learning JavaScript these days is that there is a plethora of choices for writing and running JavaScript code. In this article, I’m going to describe a few of these environments and show you the environment I’ll be using in this series of articles.

To paraphrase the title of an old computer science textbook, “Algorithms + Data = Programs.” The first step in learning a programming language such as JavaScript is to learn what types of data the language can work with. The second step is to learn how to store that data in variables. In this article I’ll discuss the different types of data you can work with in a JavaScript program and how to create and use variables to store and manipulate that data.

Professor JavaScript is a JavaScript online learning courses YouTube Channel. Students can learn how to develop codes with JavaScript from basic to advanced levels through the online courses in this YouTube channel.

Async callbacks or promises. Introduction to JavaScript Async Programming