JavaScript #1 – Getting Started

Today, most of the websites use JavaScript to make them dynamic. What means dynamic in this case? Plain HTML (HyperText Markup Language) is information for browser engines – how websites structure should be displayed. CSS (Cascading Style Sheets) is language to make them more pretty, polished and human-readable. Finally, JavaScript is language, which breathes life into websites.

The programs in JavaScript language are called scripts. They can be written right in the HTML and execute automatically as the sites loads or included from an external file. But wait… in JavaScript, you can write more than just websites. You can write mobile apps, standalone software or playable games for variety operation systems (including consoles of 7th generation).

Important is to know, JavaScript is not the same thing as Java. JavaScript is very different from another language called Java. Many years ago, JavaScript was written as LiveScript. But as it evolved, JavaScript became a fully independent language, with its own specification called ECMAScript (today, the standard is version 6), and now it has no relation to Java at all.

For instance, in-browser JavaScript is able to:

  • Append new HTML, modify existing content and styles.
  • React to users actions.
  • Send requests over the network to remote servers, download and upload files (AJAX).
  • Remember the data locally with local storage.
  • Run without compilers and external software (browser engine is enough).

But, in-browser JavaScript isn’t able to:

  • Directly execute software, read and write files from hard drive.
  • Automatically use microphone or webcam (user will be asked about permissions).
  • Grab pieces of information from any websites (some need valid headers, or has denied header-origin properties).

To sum up, JavaScript is the powerful language with some limitations. Firstly they were released for in-browser usage. Today you can write with JavaScript many different apps. So, it is worth to learn and know how and where they can be implemented.

 

Herbaciarz

 

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