Basic code on javascript

JavaScript First Steps

In our first JavaScript module, we first answer some fundamental questions such as «what is JavaScript?», «what does it look like?», and «what can it do?», before moving on to taking you through your first practical experience of writing JavaScript. After that, we discuss some key building blocks in detail, such as variables, strings, numbers and arrays.

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Prerequisites

Before starting this module, you don’t need any previous JavaScript knowledge, but you should have some familiarity with HTML and CSS. You are advised to work through the following modules before starting on JavaScript:

Note: If you are working on a computer/tablet/other device where you don’t have the ability to create your own files, you could try out (most of) the code examples in an online coding program such as JSBin or Glitch.

Guides

Welcome to the MDN beginner’s JavaScript course! In this first article we will look at JavaScript from a high level, answering questions such as «what is it?», and «what is it doing?», and making sure you are comfortable with JavaScript’s purpose.

Now you’ve learned something about the theory of JavaScript, and what you can do with it, we are going to give you a crash course on the basic features of JavaScript via a completely practical tutorial. Here you’ll build up a simple «Guess the number» game, step by step.

When you built up the «Guess the number» game in the previous article, you may have found that it didn’t work. Never fear — this article aims to save you from tearing your hair out over such problems by providing you with some simple tips on how to find and fix errors in JavaScript programs.

After reading the last couple of articles you should now know what JavaScript is, what it can do for you, how you use it alongside other web technologies, and what its main features look like from a high level. In this article, we will get down to the real basics, looking at how to work with the most basic building blocks of JavaScript — Variables.

At this point in the course, we discuss maths in JavaScript — how we can combine operators and other features to successfully manipulate numbers to do our bidding.

Next, we’ll turn our attention to strings — this is what pieces of text are called in programming. In this article, we’ll look at all the common things that you really ought to know about strings when learning JavaScript, such as creating strings, escaping quotes in strings, and joining them together.

Now we’ve looked at the very basics of strings, let’s move up a gear and start thinking about what useful operations we can do on strings with built-in methods, such as finding the length of a text string, joining and splitting strings, substituting one character in a string for another, and more.

In the final article of this module, we’ll look at arrays — a neat way of storing a list of data items under a single variable name. Here we look at why this is useful, then explore how to create an array, retrieve, add, and remove items stored in an array, and more besides.

Assessments

The following assessment will test your understanding of the JavaScript basics covered in the guides above.

In this assessment, you’ll be tasked with taking some of the knowledge you’ve picked up in this module’s articles and applying it to creating a fun app that generates random silly stories. Have fun!

See also

An excellent resource for aspiring web developers — Learn JavaScript in an interactive environment, with short lessons and interactive tests, guided by automated assessment. The first 40 lessons are free, and the complete course is available for a small one-time payment.

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JavaScript Basics and Cheat Sheet (for beginners)

A comprehensive theoretical introduction to JavaScript plus 10 items Cheat Sheet.

Editor

Hello! This article aims to help beginners accommodate JavaScript concepts. For newcomers, JavaScript is known to be the most popular language in the world with over 69.7% of use in software development. If you’re going to put aside time and energy to learn a new programming language or to get your career started in tech, you’ll want to make sure you’re picking a useful and a high in-demand programming language among a lot of languages, JavaScript is easily the best choice for you here.

• 👉 What is JavaScript
• 👉 JavaScript Basics
• 👉 Using JS in HTML
• 👉 Calling an external JS file
• 👉 JavaScript Comments
• 👉 Commons Methodologies in JS
• 👉 JS Cheat Sheet — 10 items
• 👉 Conclusion & Links

Now that you’ve done your research and probably kickstarted your learning, you might have found some of the concepts of JavaScript ambiguous and difficult to wrap your head around; don’t worry, we’ve all been there and that is why we’re putting together this article to help you learn and understand the basics of this awesome language while also giving you career-advancing cheat sheets to take your JavaScript mastery to the next level.

This article is for beginners and entry-level engineers who are looking to advance their JavaScript skillset and understanding of the language. This article contains explanations, example code, basic and important operators, functions, methods, classes, and a general overview of the basic principles of JavaScript .

✨ What is JavaScript

JavaScript in the simplest form is a programming language that powers most dynamic behaviors on a website because it has APIs that work with text, data structures, and Document Object Model (DOM). It was developed in 1995 and it is a high-level multi-paradigm scripting language that supports functional, imperative, and event-driven programming styles.

Some of the uses of JavaScript include:

1. Loading of web page content via WebSockets or Ajax.
2. Initialize pop-ups, queries, and manipulate elements
3. Control streaming media playbacks, e.t.c.

Popular websites that run on JavaScript include Google, Facebook, Youtube, Instagram, and so much more. This makes it the most used language in the history of the internet. Owing to this fact, there’s just so much to learn and it’s impossible to know all the concepts of the language memorized in your head which makes this article very important for your growth as a JavaScript developer.

✨ JavaScript Basics

Here are some basic concepts in JavaScript you should be familiar with:

To include JS in an HTML page, you’ll need to wrap the code in tags. Here’s an example of this concept:

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Open-Source Drag & Drop Builder

Open-Source visual tools built with VanillaJS that allow to code websites, landing pages and forms with ease — provided by AppSeed.

Django File Manager — #FREE Sample

Open-source Django starter that provides an easy and intuitive way to manage the files saved in the MEDIA directory — Sources saved on GitHub.

Django Dynamic Services #VIDEO

Learn how to generate services like API and DataTables in Django without manual coding — Sources saved on GitHub.

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JavaScript Tutorial

JavaScript is the world’s most popular programming language.

JavaScript is the programming language of the Web.

JavaScript is easy to learn.

This tutorial will teach you JavaScript from basic to advanced.

Examples in Each Chapter

With our «Try it Yourself» editor, you can edit the source code and view the result.

Example

My First JavaScript

Use the Menu

We recommend reading this tutorial, in the sequence listed in the menu.

If you have a large screen, the menu will always be present on the left.

If you have a small screen, open the menu by clicking the top menu sign ☰ .

Learn by Examples

Examples are better than 1000 words. Examples are often easier to understand than text explanations.

This tutorial supplements all explanations with clarifying «Try it Yourself» examples.

If you try all the examples, you will learn a lot about JavaScript, in a very short time!

Why Study JavaScript?

JavaScript is one of the 3 languages all web developers must learn:

1. HTML to define the content of web pages

2. CSS to specify the layout of web pages

3. JavaScript to program the behavior of web pages

This tutorial covers every version of JavaScript:

• The Original JavaScript ES1 ES2 ES3 (1997-1999)
• The First Main Revision ES5 (2009)
• The Second Revision ES6 (2015)
• All Yearly Additions (2016, 2017, 2018, 2019, 2020)

Learning Speed

In this tutorial, the learning speed is your choice.

If you are struggling, take a break, or re-read the material.

Always make sure you understand all the «Try-it-Yourself» examples.

The only way to become a clever programmer is to: Practice. Practice. Practice. Code. Code. Code !

Commonly Asked Questions

You don’t have to get or download JavaScript.

JavaScript is already running in your browser on your computer, on your tablet, and on your smart-phone.

JavaScript is free to use for everyone.

My Learning

Track your progress with the free «My Learning» program here at W3Schools.

Log in to your account, and start earning points!

This is an optional feature. You can study W3Schools without using My Learning.

JavaScript References

W3Schools maintains a complete JavaScript reference, including all HTML and browser objects.

The reference contains examples for all properties, methods and events, and is continuously updated according to the latest web standards.

JavaScript Quiz Test

Test your JavaScript skills at W3Schools!

JavaScript Exam — Get Your Diploma!

Kickstart your career

Get certified by completing the course

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