JavaScript is a multi-paradigm programming language that is commonly used as an embedded tool for programmatic access to various application objects. From a web development point of view, it is impossible to create modern interactive websites without knowledge of this technology. The JS language is what “animates” the markup of pages (HTML) and user functionality (CMS) of websites. With this language realized the possibility of the reaction of the page or its individual elements to the actions of the visitor. Today JavaScript is the basic programming language for browsers. It is fully compatible with Windows, Linux, Mac OS, and all popular mobile platforms.
How the technology works
Now it is necessary to understand what JavaScript is in terms of operation. All user actions in the browser window create events, and JS programming allows to process them in a certain way.
The standard operating algorithm looks like this:
- The user performed a certain action.
- The browser has detected an event.
- JS-code is activated.
- On the page the specified change occurs.
The task of the programmer is to create handlers for all the events to which the site should react when interacting with the user. For clarity, here are two examples of typical scenarios.
- The user clicks on the left mouse button.
- The browser captures the onclick event.
- The changePhoto function is activated.
- In the photo viewer, the image is changed.
If the handler is not embedded into the code, the algorithm is about the following:
- The user makes a click.
- The browser locks the onkeydown event.
- There is no special JS-code to process this event.
- After the click nothing happens.
It should be noted that programming is not always tied to the user’s active actions. For example, the JavaScript-code can be triggered when the page is fully loaded, or after a certain amount of time spent on the site. These features are actively used to create pop-up elements and chat rooms.
Positive features of the technology
What it is – JS, and how it works, we found out. But why is this programming language so widespread? The main advantage is considered a full integration with HTML, allowing you to transform the page without restriction. With the help of JavaScript specialist can:
- quickly integrate into the code of the page any tags;
- determine the appearance of elements;
- Perform positioning of objects;
- retrieve user data;
- Interact with the server (AJAX).
And that’s just the basic and most used features of the technology. Application of JavaScript allows you to do within the page almost everything you need.
How JavaScript is limited
In its pure form, in other words without any special add-ons, the JS language can only function in the browser. Even so, there are security restrictions. For example, JavaScript can only close the tab that was created by it. In general, this programming language is designed for browsers and the Internet, and outside of them it should not be used.