What is javascript used for? What are JavaScripts? Basic JavaScript Features

Previously, I did not think that the Internet could provide such extensive opportunities for developing my business, but time passed and I finally discovered this world, full of possibilities. The Internet provides an opportunity to sell your products, a wide variety of them. Every day the number of users world wide web is growing, and at the same time our capabilities are growing.

Once upon a time I didn’t understand many earning schemes, but today I can say with complete confidence that the basis of any business in global network lies the website. Moreover, not just a site, but the right site. Moreover, many factors influence whether the site will be profitable. The first thing a visitor to any website encounters is the interface.

Believe me, how attractive the site is will determine whether a casual user will stay on it or not. Of course, if a person has been reading your site for a long time, then he will forgive you for various mistakes that you may make in the functionality of the site. But for the first time, the interface will play a key role in making the client like your website. As they say, “they are greeted by their clothes, they are seen off by their minds.”

But in order to make original and memorable clothes for your site, you will need to know what javascript is for. In fact, without JavaScript it is impossible to create a beautiful, functional website. Moreover, there will be no need to clutter the site with tons of code. It will be enough to add just a couple of lines, and different buttons and the menu items will “come to life” and become more attractive. By the way, a JavaScript script will allow you to scroll through pictures in your portfolio. In addition, you can further increase the functionality of the page when displaying data. JavaScript is also needed here

Perhaps many may think that, for example, it works on a good CMS, and to manage such a blog you do not need JavaScript knowledge at all. On the Internet you can find many different modules and plugins with which you can significantly improve functionality, add cool effects, etc. However, we should not forget that web technologies do not stand still, everything is constantly changing. Therefore, it is worth constantly monitoring the emergence of new JavaScript libraries, after all, it is possible that today’s packages will make it possible to realize what only yesterday seemed just a dream. That’s why when they talk about updating a site, they also mean the use of JavaScript.

Now as for learning JavaScript. For some reason, many people believe that learning this programming language is only available to a select few. But actually it is not. Web programmers are constantly working on creating new JavaScript elements, which greatly simplify its syntax and use. In addition, you can use JavaScript code on the pages of your site if you know how to use the appropriate manuals. Wonderful video courses will come to the rescue with this, with the help of which even a complete layman can learn short time will be able to master JavaScript.

I express my gratitude for information support Evgeniy Popov, the author of a number of video courses on website building. Including the video course “Javascript + jQuery for beginners in video format”

Javascript is a programming language that is built into the html code of web pages to increase the functionality of the site. Javascript was developed by Netscape in collaboration with Sun Microsystems based on Sun's Java language. Java scripts are executed on the client side, although initially Liveware, the progenitor of Java Script, was server language programming.
WITH using JavaScript beautiful interactive web pages are created, which cannot be done in pure html language. Typically, scripts are executed after the user takes some action: hovering the cursor, clicking, etc. Java script can also be executed when a web page is loaded.

You can write a Java script using any text editor: Notepad, Notepad++, Dreamweaver. In the latter, in addition to code highlighting and hints, a syntax check for writing javascript is implemented. But for this you need to know the language, the principle of writing functions, methods, properties, etc. And to view you only need a browser capable of processing Java scripts. For example, Mozilla Firefox with a built-in Firebug add-on, with which you can view the work of javascript itself and Microsoft Internet Explorer (since the two browsers handle javascript differently).
By the way, not all scripts are displayed equally in browsers. Most of the Java scripts that can be downloaded for free on the Internet are not supported at all by the Opera browser up to version 12.16. At the same time, the operation of JS does not depend in any way on operating system: be it Android, iOS, Windows or others.

Download ready-made JavaScript code.

Below are ready-made Java scripts that you can
download completely free of charge and decorate your website with them.

Javascript hosting.

Javascript code can be placed either on the page itself or in a separate file.

An example of placing ready-made Javascript code inside HTML.

Scripts written in javascript can be located on the html page itself between tags, which in turn are usually located within tags. The tag must have a single parameter "type", which indicates the type of script writing:

Theoretically, tags can also be located in the body of the document (in tags). This scenario will be executed when the browser “reads” the page to this point (to the tags).

If you don't know language Javascript, then you can download the ready-made script code for free and place it as described above on your website.

An example of placing ready-made Javascript code in a separate file.

We create in any text editor page and save it as ....... .js . Next we download ready Javascript code and put it on this page. We save it in the same folder as the HTML. Now you need to connect the Java script to the html page. For this purpose in HTML file We make the following entry:

src="path to file.... .js".
Now they remain only in the right place web pages call a function that describes the necessary actions

function name - executed when the page is loaded

link - javascript will be executed when the link is clicked.

onLoad event

The event occurs after any page element is loaded.

onClick event

The event occurs after a mouse click.

onMouseover event

The event occurs when the cursor hovers over a specific page object.

onMouseout event

The event occurs when the mouse cursor moves away from the object.

JavaScript is a special type of programming language that is based on browser object representations. It is necessary in order to provide the site with greater interactivity compared to conventional static HTML documents. For example, in the interface custom type It will be possible to implement changing pictures, a creeping line from text content and much more! That's why it's important to know how to enable JavaScript in Firefox and other browsers.

JavaScript differs in that the text of software developments is embedded in HTML documents and parsed by the browsers themselves. JavaScript is a language for programming scripts on web pages.

Types of differences between JavaScript and Java

Knowing the designation of the term JavaScript, many users indiscriminately confuse this type of term with another concept - Java. Although the languages ​​are similar due to their names, they have different types values. The main types of differences are in difficulty and in the number of advanced types of opportunities. Before you learn how to enable JavaScript browser, it is necessary to understand its characteristic features.

The implementation of "JavaScript" is more free compared to Java. For example, data type conversions occur in the simplest way. Also, the programmer will not need to compile the initial software development code on JavaScript, in other words, it is an interpreted type of language.

How does this happen in JavaScript and in Java? In JavaScript, the program processes one line after another, informing about errors is issued after each line read, if there are any. In Java, the compiler shows these types of information after reading the complete text of the software design.

Before you enable JavaScript, remember that it is not intended to be a language replacement. Java programming. It is best to use the first type of language as a complement to the second.

Why is JavaScript needed?

With JavaScript support you can create dynamic types HTML documents. Static Views HTML pages gone into the past tense. "JavaScript" connects all the building blocks of applications into a single whole. In other words, it serves as a foundation builder, doing checks on HTML form fields until they are submitted to the server. Knowing how to enable JavaScript in Firefox and other browsers is essential for them to work correctly online.

Management software developments in this programming language go through local administrations communication data. Users have the opportunity to observe in various windows the types of warning messages that are displayed with JavaScript support.

What's happened JavaScript error and how to run JavaScript

Let's start with the fact that JavaScript makes it possible to add various interactive services to any website, safely add voting (surveys) and similar content without the risk of unnecessary page reloading. In these cases, types of scripts significantly help save user traffic and allow you to copy graphics High Quality, create types of galleries with images and do many other functions utility type. But then, in order to run types of scripts, you first need to activate them.

Next, you need to remember about the usual types of problems of network users. In recent times, there has been an increase in situations where a person, having visited his page on a social network, finds error messages at the top of the windows: “JavaScript error”, “JavaScript is not enabled”, “For correct operation JavaScript must be enabled on the site." In such cases, users have problems uploading photos and videos on the social network.

How to enable JavaScript in Firefox

In fact, the method of running scripts is very simple, you only need to perform a few elementary actions that can do even the most inexperienced users. Step-by-step instruction as follows:

• first you need to start personal Mozilla browser Firefox;
• after that, open the browser options, then click on the corresponding button in the form of three parallel lines next to the introduction line;
• now a huge window with many tabs has opened in front of you; the one you need is called “Content”, click on it;
• then it’s even simpler: find the line “Use JavaScript” and check the box next to it;
• Click "OK" and restart your personal browser.

At this point, the instructions on how to enable JavaScript in Firefox can be considered complete.

Disabling JavaScript

Accordingly, if the need to use JavaScript is no longer necessary, you can disable it in the same way as written above this type functions. To do this, also go to “Settings” - “Content”, uncheck the box next to “Use JavaScript”. Ready!

Additionally, if your Mozilla Firefox browser is updated to latest version, then it would be good to check whether the settings have been lost after updates, as sometimes this happens. It is also worth noting that almost all types of social networks use interactive types of forms, therefore, without the included types of scripts, it will not be possible to fully view pages.

I can be unavailable messages, alerts, discussions. Sometimes failures occur, and if in social networks Some types of sections suddenly became inaccessible, but at the same time there are types of scripts activated in the browser, try turning them off and then turning them on again. Perhaps this method will solve the problem. If not, then there is always the option of resetting the options to standard. How to enable JavaScript in Internet Explorer and in other browsers? The same way.

In this article we will tell you what JavaScript (Java Script) is, give examples, and explain why it is needed in html code. We will provide answers to popular questions from webmasters.

1. What is JavaScript simple words

JavaScript (in Russian "Java Script", abbreviated as "JS") is a programming language built into HTML pages for the purpose of ease of communication with the user, error handling and creating dynamism of the page as a whole.

JavaScript is an object-oriented and interpreted language. It is system independent (works on any platform). JS code is often called scripts. We can say that this language is “tailored” only for web programming.

The syntax of the language is in many ways reminiscent of C and Java, but semantically the language is much closer to Self, Smalltalk.

2. Problems solved by JavaScript

• Field checking html forms(tag) before they are sent to the server
• Information messages with warnings
• Effects for highlighting main elements and parts of the page
• Original drop-down menus
• Mathematical calculations

Sliders are usually made using JavaScript. You can also display content via AJAX output, this allows you to hide unnecessary or repeated elements of a site page from the html code. It makes no sense for a beginner to study these codes, because... they are quite complex.

3. How to enable JavaScript support in the browser

All browsers support JavaScript. By default, Java Script should already be enabled in browsers, if not, then below are instructions for different browsers by including JS.

1. Enable JavaScript in Firefox 2. Enable JavaScript in Google Chrome

"Settings and Google management Chrome" -> "Options" -> "Advanced" -> "Personal Information (Content Settings)" -> "JavaScript:" Allow all sites to use JavaScript (recommended) or disable JavaScript execution on all sites

3. Enable JavaScript in Opera

Press the F12 key Select "Enable JavaScript"

4. Enable JavaScript in Internet Explorer

"Tools" -> "Internet Options" -> "Security" tab -> select the "Internet" zone -> "Other" button -> "Scripts" -> "Allow scripts"

4. Example: how to insert JavaScript into an html page

The JavaScript code fits directly into the html code of the page. To highlight it, use special tags

javascript code

The type="text/javascript" attribute is not required, but recommended.

You can use ‹script› in title tags or simply in the body of the page.

Write html tags between the opening and closing script tag is not allowed. This place is for JavaScript code only.

In order not to duplicate the same JavaScript on each page, it is usually placed in separate file with the extension ".js". This file can be included anywhere in the html page.

4.1. Example 1: Hello, World Pop-up Message

Below is an example of html code that displays a pop-up message "Hello, World" when the page loads.

Hello, World in JavaScript

Example with Alert. A pop-up message will be displayed

alert("Hello, World!");

Click on the link:

Link4.2. Example 2. Alternative with javascript processing

Below is an example html code with processing JavaScript code using id.

Hello, World in JavaScript window.onload = function() ( var linkWithAlert = document.getElementById("check_link"); linkWithAlert.onclick = function() ( return confirm("Follow the link? "); ); );

Click on the link :

Link4.3. Example 3. Changing the color of an object on hover

When you hover your mouse over certain areas, they change color. This is done through JavaScript. For example

Code for this example:

RED GREEN BLUE

This is just the most basic JavaScript stuff. Its capabilities are quite large. It’s not for nothing that you can find separate books on this language in literary stores.

Today, there is probably no website that is not written using javascript.

The use of this script has become so popular that it is now simply impossible to do without it. The only people more popular and famous than javascript today are probably Paris Hilton and McDonalds.

What exactly is he?

Javascript is a scripting language whose purpose is to create interactive web pages. It works as is, without requiring compilation, but simply connecting to the HTML page. It should not be confused with Java - even if the names of these two languages ​​are similar, this does not mean that they are functionally related. In fact, it is much closer, for example, to Ruby or Python, but has its own ECMAScript standard, and therefore is still separate from them.

What Javascript Can Do

Javascript can do a lot - for example, it can be used to easily change element styles, remove tags, or add new ones. In this case, you can set the function in such a way that the script reacts to certain events - either mouse or key clicks, or begins to act on its own after some time has passed after loading. And with AJAX you can get updated data without reopening the page.

Javascript is capable of setting and reading cookies, displaying messages, windows, validating data, and much, much more. Handyman.

Javascript has three main advantages, including, for example, accessibility (by learning the basics of JavaScript, you can easily understand most of them and always improve your skills); universal support (they are supported in almost any computer environment - any modern computer capable of this), as well as full browser integration, making javascript even more convenient and easy to use.

As an example, we can cite technologies like VBScript, XUL and ActiveX - they are not supported in every browser and only work in a certain environment.

And of course, we must not forget about the speed and efficiency of JavaScript, which makes many programming languages ​​pale in comparison.

It would not be amiss to note that even now this technology continues to develop, and at a rapid pace - just have time to keep up! And soon a new interpreter will be created along with javascript technology 2.

Advantages

JavaScript has many advantages, otherwise it would not be used so actively. It earned the love of users for a reason. One of its main advantages is considered to be interactivity, which is why most sites are written in this language. This is achieved thanks to the AJAX tool, and with its help the data will update itself, without user interaction. This is very convenient, for example, on payment system websites. This will be very useful for not the most experienced users - real help from the script itself that you use. What could be better?

Now I’ll tell you a little about the structure of this language.

• JavaScript has several features, including the following:
• Identifiers are case sensitive;
• Variable names can include the "$" symbol, underscores, numbers (but cannot begin with them), and letters;