Learning javascript from scratch. JavaScript tutorial for beginners from Dmitry Trepachev

JavaScript is primarily a client-side language, typically used for client-side work. With its help, you can develop applications with a wide variety of functionality. This could be: an analogue of a mechanical watch, various animations, graphic effects and more. Nothing prevents you from creating almost the entire web application in JS.

Today it is difficult to overestimate the role of JavaScript on the web. According to w3techs statistics, today over 95% of websites use JS. The remaining 5% are mainly business card sites and one-page websites. The incredible popularity of the language makes it one of the most desirable for learning and profitable in terms of future employment.

Founded in 1995 by Netscape. Initially intended as a scripting language for their Navigator 2 browser. At the beginning, it was called LiveScript. The developers took advantage of the wave of popularity of Java and changed the name to JavaScript. However, to this day they are often confused by novice developers. Many claim that these are the same languages ​​or have minor differences. This is not true at all, JS and Java are completely different languages. The only similarity between them is their names.

Initially, JS did not have most of the functions available today; its capabilities were extremely meager. The main goal was just to add a little interactivity to the page. The developers wanted the results after button clicks to be processed within one page.

As the web developed, along with the release of , JavaScript received carte blanche to actively develop many functions. Today, JS provides many more developer options than ever before.

JavaScript can now be used as a server-side language. Previously, JS was always considered purely as a client-side language that ran exclusively in the user's browser. To work with the server, I had to use something like , . This made it possible to operate requests on the server using JS.

Despite the ability to implement the server side in Node JS, most of the web uses PHP for this. This is not only the result of habit, but also of the lack of need for another language.

In the modern world, there is a boom in development for mobile devices, where JavaScript has found a place. This contributes to increased productivity of mobile gadgets and the widespread use of HTML5. JS allows you to implement a wide variety of features even in mobile applications.

Due to the release of new versions of Windows from 8 and newer, JavaScript began to be used to develop desktop applications for the listed operating systems. In other words, JS has long gone beyond the scope of a web language that is used exclusively by the browser.

Much of what was once called science fiction is now successfully implemented in JavaScript. This is especially clearly visible in the popular area of ​​IoT programming. Thus, JS can be successfully used to develop water programs by all existing smart devices that support the Internet. Today JS is found almost everywhere IT has reached. It is actually a popular and incredibly functional language that plans to continue to evolve.

Even during the emergence of the language, the Netscape and IE browsers created several different implementations of the language. To unify all implementations and restore a common denominator, the ECMAScript standard was developed (ECMA took over the management of standardization). If you see the term ECMAScript anywhere, it is an interchangeable synonym with JavaScript.

Already today, ECMA has developed a couple of standards for JS; they successfully reflect progress in the development of the language itself. Today, ECMAScript 6 version from 2015 is considered current. However, many browsers are still far from fully implementing this standard. It may take several more years to complete its implementation. For this reason, ES5 is often considered to be the standard that is fully supported by modern browsers.

JavaScript is an interpreted language, meaning it is executed through an interpreter. It receives all the necessary instructions from JS and follows them by executing or interpreting the code.

Development Tools

To create code in JS, you just need a text editor and a browser in which you can test the result. One of the simple and functional text editors that I would recommend using is Notepad++. In general, you can use any convenient one.

JavaScript also supports a number of development environments, such as Visual Studio, WebStorm, Netbeans. They help you create code much faster and easier.

Additional courses

On our website you can find additional courses on the JavaScript language. All courses are presented on.

Adapted translation of the article “Full-Stack JavaScript in Six Weeks: A Curriculum Guide”

Web development is one of the simplest and therefore popular areas among novice programmers. Any text editor and browser is enough to work; there is no need to study algorithms at an advanced level, the result of each stage of writing a program is clear - in general, there are many advantages. A key skill in the context of web development is knowledge of JavaScript.

Nowadays JavaScript is developing very quickly, and therefore it is easy to get confused when learning the language. We offer you a well-structured curriculum that covers all the essential aspects of JavaScript and related technologies.

Why JavaScript?

It is worth noting the openness of the language - companies that usually compete with each other are collaborating to develop JavaScript. The language is very flexible and will suit supporters of both object-oriented and functional approaches. A huge number of libraries and frameworks make it easy to solve any type of problem, and the Node.js server platform makes it possible to use the language not only in the browser, but also in the console. You can even write desktop and mobile applications: the former using the Electron framework, and the latter using NativeScript or React Native.

Basics

First you need to learn the basic concepts of JavaScript, web development and programming in general:

• object-oriented JS - constructors and factories, inheritance;
• functional JS - higher order functions, closures, recursion;
• Jasmine test specifications;
• basics of HTML, CSS and jQuery.

Git

Git is an essential tool for developers, so get started with it as early as possible. Here are the basic skills you should have:

• creating and moving files in directories;
• initialization and commits in Git;
• setting up repositories in GitHub.

Algorithms and data structures

Next, it's worth learning about algorithms (in particular, the concept of algorithmic complexity), as well as basic data structures: linked lists, queues, stacks, binary search trees, and hash tables. This will help you.

BackendNode.js

10 years ago JavaScript could only be used for front-end development. Now, thanks to Node.js, the matter is not limited to one “front”. Node is simply an environment for running JS code on the server side, so you won't have to learn any new syntax, but you will need to import and export files, modularize code, and use the npm package manager.

Servers, HTTP, Express.js

After learning Node, it's worth continuing your acquaintance with backend development and understanding servers and routing. You can start with ports and protocols with an emphasis on HTTP, and then move on to Express, a Node library for processing requests.

Asynchronous JavaScript Databases, schemas, models and ORMs

Databases are one of the most important elements of web development. If your application needs to load or store any data that is not lost when the page is refreshed, you will have to use a database. You need to learn to distinguish between relational and non-relational databases and understand the types of relationships. Then get to know different people. The ability to work with ORM will also not be superfluous.

FrontendHTML and CSS

HTML and CSS are the foundation of any web developer. You don't have to know them perfectly, but you should understand them. You can also explore a popular library (for example, Bootstrap) and a CSS preprocessor like Sass - it will help make CSS look like regular code. To simplify working with HTML, you can choose one of the popular template engines, for example, pug.

jQuery and DOM manipulation

Once you've created the look and feel of your page using HTML and CSS, you'll also use jQuery to manipulate the DOM. Many people think that jQuery is useless and will soon be replaced by Angular and React, but it is insanely popular and therefore worth knowing. In addition, one day you will find yourself in a situation where it will be inconvenient for you to hammer nails with a React microscope, and then lightweight jQuery will come to your aid.

Chrome Developer Tools

It would be unforgivable to neglect Chrome tools, which provide a huge number of possibilities. With them you can examine DOM elements, debug via the console, trace routes, and much more. We describe several handy features of the Chrome console that will make routine tasks easier.

AJAX

If you want your application to not reload pages after every database operation, you'll definitely need AJAX - it sends background asynchronous HTTP requests, the responses to which only update part of the display. You can work with AJAX through jQuery using the .ajax method.

Advanced TopicsTest Driven Development

Or TDD is a development technique in which software creation is divided into many small cycles: first, tests are written that cover the desired change, then code is written that passes these tests. After this, the code is refactored, and new tests are written if necessary. If a section of code fails some tests, this is corrected.

Websockets

This topic is worth paying special attention to because it is very useful. The WebSocket protocol, unlike HTTP, allows for bidirectional data flow, which makes this technology unique. The most common implementation is the socket.io library - understanding it and applying the acquired skills in practice will help you create a multiplayer browser game.

ES6, Babel, Webpack

Currently, the main standard is ES6 (ES2015), but ES2016 has already been adopted, and ES2017 is in development, so you need to always be aware of updates and use them. Compatibility problems can be solved with just a couple of tools:

• Babel - compiles ES6 code (ES2016 support coming soon) to ES5, which is supported by all browsers. It even knows how to compile JSX/React components, which makes it indispensable for any web developer;
• Webpack - collects all your source files (images, fonts, stylesheets, JS files, etc.) into a single dependency graph. It won't be useful when creating small applications, but when working with React its help is invaluable.

React and Redux

React is a library for creating user interfaces. It was created by Facebook in 2013 and quickly became popular among developers. You should read and then disassemble to understand how React works and what it does. React is useful not only for front-end development: Facebook has released versions of the framework for mobile (React Native) and VR development (React VR).

Redux is a predictable state container commonly used in conjunction with React. It can be used to shorten code due to its modularity. Particularly useful in real-time, multi-user applications such as games.

Authentication, sessions, cookies

You should also understand how applications interact with users, process account logins and logouts, and grant privileges. To track the user's identity during a session, cookies are used - small text files sent by the server to the browser in response to an HTTP request. And to ensure the connection between the database and authorization pages, you can use the express-session library.

Web Security

And finally, you should pay attention to safety. It is important to learn both attack methods and ways to defend against them.

Hello, dear readers. While someone is desperately looking for something else to save on in order to maintain their level of well-being, smart people are investing in themselves. They have long realized that knowledge of technology can make good money.

How exactly? I have about 100 blog articles dedicated to this. For example, "" or "". What can we say about those who are planning to do something serious? Computer literacy among the population is growing, and with it the number of educational materials. All that remains is to find the best ones.

Today we will talk about JavaScript lessons for beginners. Knowing this programming language, you can already look for clients and earn money. For some, this will be the next step to success in the IT industry.

From today's article you will learn where you can learn to code, get a hint on how to do it as efficiently and quickly as possible, or for free. Each person has their own priorities, so I will try to fulfill everyone's hopes of finding something useful in this publication.

Contrary to custom, I won’t beat around the bush for too long. There is a lot of information. Let's get started.

Free JavaScript classes

The financial issue for many beginning programmers is of paramount importance. This is quite logical. The Internet was originally created as a knowledge base in which everyone can find information of interest. “Why do I suddenly have to pay?” is a completely natural question.

Unfortunately, the answer to this is also simple – quality. There are too few talented and unselfish people in our country who are ready to give their time for free, but don’t be upset.

Fortunately, there are all sorts of promotions, bonuses and courses created to increase the PR of developers. Little-known schools create materials, but at first, for the sake of feedback and reviews, they are ready to provide them for free. You just need to get to the right place and find the best time for it. I managed to find a good option, which I am happy to share with you now.

If you don't know anything about JS (this is the worldwide abbreviation for JavaScript), I can suggest a selection of videos from YouTube. This is an introductory course for learning from scratch, created by the online school Huxlet.

You can also get the course " Basics of programming» with tasks on the company’s official website. The 17 hours of training includes 27 lessons and 21 practical exercises.

Once the basics have been learned, you can move on to the next step " JS: preparation for work" Access is also free.

Naturally, I myself did not take this course, and therefore I cannot guarantee the quality and tell you about any features of the training. Huxlet appeared relatively recently and positions itself as an international team of specialists engaged in training people from scratch to professional level.

English-language texts, courses, references to familiar resources like Lifehacker and Habr inspire confidence. However, the main advantage, in my opinion, is that it is free.

Perhaps a little later the company will be able to prove itself, prove its importance in this world, show the level of specialists it produces and achieve fame, success and the like.

If you don’t want to waste time and study so much, you can “buy out” only the information related to JS: “JavaScript. Level one" and "JavaScript. Level two." True, I think that in this case I will have to forget about the internship. This information should be clarified with the developers.

That's basically it. I wish you all the best. Don’t forget to subscribe to my VKontakte group to know a little more about making money on the Internet. Until next time.

This page is the beginning of a JavaScript tutorial for beginners. To master it, you need to have at least minimal knowledge of HTML and CSS. Refer to the HTML and CSS tutorial for beginners to get them (to learn JavaScript you need to take at least 3-4 lessons minimum).

JavaScript is designed to run in the browser alongside HTML and CSS. But, if these languages ​​are intended for layout of the site structure, then JavaScript allows you to “revive” web pages - make them responsive to user actions or demonstrate some dynamism (for example, changing pictures in a block or beautiful smoothly drop-down menus).

So, without further ado, let's get started learning this undeniably useful language.

How to run JavaScript

There are two ways to write and run JavaScript: the first is that we write the code directly on the HTML page inside the tag:

This is the title title var name = "Dima"; alert("Hello, "+name);

The tag can be placed anywhere on the page - both in and in .

The second option is that the JavaScript code is stored in a separate file (like CSS) and is also connected using a tag with the src attribute, which specifies the path to the file with the script:

This is the title title This is the main content of the page.

In the future, I will not describe how JavaScript is connected, but will simply write HTML code in one block, and JavaScript code in another.

Finding errors in the code

Watch the following video where I show how to work with the debugger, which shows JavaScript errors, and the console:

• Lesson No.
  playlist on YouTube
  Practical Application of ES6

Some videos may get ahead of themselves, as we haven’t covered all of ES6 yet at this point in the tutorial. Just skip these videos and watch them later.

AJAX

• lesson excluded (little material), there will soon be a separate textbook on Ajax (lots of material)

This is an introductory course to JavaScript for beginners. In terms of priority, this is the third subject that a competent web developer needs to know. The first two are HTML and CSS, of course. Welcome!

The JavaScript scripting language was developed by Brendan Eich in 1995 as one of the extensions for the Netscape Navigator 2.0 browser, which few people remember. But the language itself lives and flourishes.

Unlike HTML and CSS, it is already a real programming language. We can say that HTML and CSS are just flowers, but JavaScript is like berries. They differ fundamentally. HTML is simply the markup (or otherwise, the structure of the site), and CSS is the appearance of this markup. But JavaScript allows you to create programs that instruct the user’s computer to perform active actions.

Therefore, if you don’t yet know even such simple things as HTML and CSS, then it’s clearly too early for you to take on JavaScript.

But there is no need to be afraid. Unlike its big brothers like Java or C++, JavaScript is a fairly simple language. Any beginning web developer can master it. In any case, learning to use it is not at all difficult.

Programs that are written in JavaScript are called scripts or scripts. It should be clearly understood that these scripts are executed only on the user’s computer, and not somewhere on the network. Therefore, they largely depend on the settings of the same browser that the user has set. If he deliberately disabled the scripts, then they simply will not work.

Why is JavaScript needed?

Why use any scripts on the user side at all? The key word here is event handling. Such an event could be, for example, a click on a button in a data submission form. For this purpose, special attributes starting with on are provided.

Examples of such attributes:

onclick - single mouse click;
onmouseover - placing the mouse cursor in the area occupied by any page element;
onfocus - highlighting (focusing) an element. For example, form fields where the cursor is placed.

Okay, you might say, why use some JavaScript to process the same form? There is php for this. I filled out what was required and sent it to myself in peace.

That's right, JavaScript doesn't process the data, PHP does that on the remote server.

But what if the user did not fill out everything? If, for example, you missed required fields marked with an asterisk *. What then? Then a new page will fly to him from the server, on which it will be written what a sucker he is.

The fundamental difference here is this: without using JavaScript when submitting a form, the request will be sent to the remote server in any case, even if the form is filled out incorrectly or incompletely. And an error response will be received from the server. The user will have to enter everything again. And so every time. And if you use JavaScript, the page with the form will not be sent to the server until the user enters the correct data.

That is, the script, as they say, “without leaving the checkout,” will check the form directly in the user’s browser and display a message if it is filled out incorrectly or insufficiently. Here he acts as a supervisory authority.

Agree that this is much more convenient, takes less time and, of course, eats up less traffic. And in the case of a mobile connection to the site, this is even more significant.

Thus, JavaScript scripts are convenient helpers that not only check the entered data, but also perform a lot of useful actions on the user’s side. Take, for example, the same drop-down menu lists or collapsible windows, all kinds of sliders and spectacular image galleries, highlighting of active form fields or tooltips on website pages, and much more.

An advanced reader will say:

Ha! So all this can be done using pure CSS3 without any scripts!

I agree, except for the word “everything”. All but not all. You can create all sorts of tricks and tricks using pure CSS3, but CSS cannot verify that the form is filled out correctly. And besides this, there are thousands of other ways to use JavaScript scripts for more serious things. Otherwise, smart people wouldn’t cram JavaScript into Bootstrap or create a mega-useful library of jQuery scripts.

How to include JavaScript in a website page

There are several options for connecting JavaScript on site pages.

1. Small JavaScript code can be embedded directly in HTML tags. For example, the following code will display the text “Enter your E-mail” in the form field, which will automatically disappear when the cursor is placed there so as not to disturb the user:

As you can see, it is not specifically indicated anywhere that this is JavaScript, but browsers understand this and process it according to the written commands.

However, JavaScript makes extensive use of the same characters that are used in HTML. For example, angle brackets or straight quotes. To prevent the browser from making a mistake in interpreting these characters, scripts are usually written between special tags:

2. Slightly larger JavaScript script code can be added directly to the location on the page where you want it to fire. As mentioned above, we frame it with tags.

But this is not always convenient, and in some cases it is fraught.

For example, if the user has disabled scripts in his browser, the page may freeze at this point and not load completely. Therefore, it is generally recommended to place scripts at the very bottom of the page, before the closing tag. In this case, even if the script does not work, the page itself will load entirely and without unnecessary delays.

3. The most correct way to connect JavaScript scripts is to put them in a separate file with the .js extension and connect them to the page via a link, as is the case with a CSS style sheet placed in a separate file. Example:

This concludes our introductory excursion into JavaScript. Next time we will write our first script in this wonderful language. Subscribe to Web Council blog updates so you don't miss anything!