JavaScript from A to Z

By on January 11, 2019

It is widely believed that one of the very first programming languages that almost every software programmer choose to start with is JavaScript which is considered the most popular and trustful programming language in website building. JavaScript, as well as any other programming language, is one key foundation of nowadays software technology inventions and innovations.

So welcome, those who have ever wondered about this powerful technique, how it’s formed and how it works. And especially, those who have just entered the breathtaking Journey to Become a Coder. Let’s get to know more about JavaScript.

What is JavaScript?

What everyone has already known: JavaScript is a worldwide-used programming language. What you might be not aware of: It is characterized as weakly typed, prototype-based, dynamic, and multi-paradigm. JavaScript is one of the three core technologies of the World Wide Web (www), alongside HTML and CSS. Therefore, JavaScript is not only an essential part of web applications, it can also help enable interactive web pages. In short, it’s like a full-fledged programming language embedded inside your web browser

What can you do with JavaScript?

The vast majority of websites and mobile browsers has been using JavaScript engine, including Chrome, Firefox, Edge, Safari, Internet Explorer, Opera, etc. Besides ordinary functions of a regular programming language such as declare variables, store and retrieve values, define and invoke functions, define your own classes, load and use external modules, etc. As a client-side framework (what is client-side and service-side), JavaScript is also primarily used to enhance responsibility and user interface of web pages to provide users a better experience. For example, creating menus, dialog boxes, animations, 2D/3D graphics, interactive maps, video players, and much more.

Warning: Since JavaScript is such a powerful language, it is also totally possible to use it to write malware, viruses, browser hijackers and other nasties which will pose a serious threat to users. These range from stealing browser cookies, passwords, credit cards to sending viruses to your computer. Everything is a double-edged knife, be a wise leaner and use your knowledge well.

How it works

Now let’s have a look at the main syntaxes of the JavaScript language to give you a clearer understanding of how it works. It is worth noting that these features are common to all programming languages, so if you master these fundamentals, you’re doing well on your way to become a real professional coder that is able to write codes for just about anything!

  • Variables in JavaScript can be defined using either the var, const or let keywords.

  • A simple recursive function:

  • An anonymous function (or lambda):

This example shows that, in JavaScript, function closures capture their non-local variables by reference.

  • In JavaScript, objects are created in the same way as functions, this is known as a function object.

  • Variadic function demonstration

  • Immediately-invoked function expressions are often used to create modules, as before ECMAScript 2015 there was no built-in construct in the language. Modules allow gathering properties and methods in a namespace and making some of them private

Using JavaScript to create a simple “Hello World” Heading for your site

  1. Firstly, go to your test site and create a new folder named ‘scripts’ (without the quotes). Then, within the new scripts folder, create a new file called main.js and save it into the scripts folder.
  2. Next, in your index.html file, enter the following syntax on a new line before the closing </body> tag:
    <script src=”scripts/main.js“></script>
  3. This is basically applying the JavaScript to the page to create an effect on the HTML (alongside the CSS and anything else on your page).
  4. Now, add this code to the main.js file:
    var myHeading = document.querySelector(‘h1’);
    myHeading.textContent = ‘Hello world!’;
  5. Last, make sure the JavaScript files and HTML are well saved, then load index.html to the browser. If  you have done everything well, this is the result: Your heading text has now been changed to “Hello world!”, absolutely.

Explanation: You did this by first grabbing a reference to your heading, and store it in a variable called myHeading, using a querySelector function. The first thing you need to do with an element is to select it. The code you wrote after that is to set the value of the myHeading variable’s textContent, which represents the content of the heading, to “Hello world!”.

This is just a basic sample of using JavaScript creating heading for your website. In most real cases, writing a code to build businesses’ websites needs to combine more than one programming language and more complex syntaxes.

So if you happen to need support from professional and experienced software development company with your upcoming project, or you’ve just passed through your coding journey and now looking for opportunities to join the coolest software programmer squad ever, Designveloper is right here waiting for you!

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An exceptionally ordinary Story Teller walking in a World floating above a Horizon. Imagination can only touch souls when it comes along with reality.

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