Introduction to JavaScript

What is JavaScript?

JavaScript is a programming language that all major web browsers are capable of executing without any extra installations or extensions. JavaScript allows us to add interactivity to an otherwise static web site; we can show videos, animated 2D/3D graphics, send and receive network requests and much more.

Modern web sites use JavaScript everywhere to create better desktop like experiences right in our browsers. JavaScript combined with HTML and CSS is capable of almost anything you can think of.

What can we do with it?

  • Create inputs and elements that remember use input values and can store and use them later
  • Manipulate numbers, text and other types
  • Run code when a user triggers a specific event
  • Fetch data from other websites and APIs
  • Much more (as we will discover in this course)


JavaScript was created by Brendan Eich in 1995 while he was working at Netscape, which at the time was behind the world's most used web browser: Navigator.

Brendan Eich at the Web Direction Conference in 2010. [Image by Drew McLellan]
Brendan Eich at the Web Direction Conference in 2010. [Image by Drew McLellan]

JavaScript, despite its name, does not share many similarities with the object oriented programming language Java. JavaScript was initially named LiveScript, but was renamed to JavaScript as a way of marketing the language using Java's popularity.

JavaScript was later on copied by Microsoft in Internet Explorer where it was renamed JScript. Internet Explorer's market share continued growing over the next years, and ended up with a 95% market share by the early 2000s.

The standardization of JavaScript (ECMAScript) started off well with all major web companies (Microsoft, Mozilla, Netscape) contributing to a common standard until Microsoft decided it wasn't worth the effort since everyone used Internet Explorer anyway. The ECMAScript standard was left for dead until 2008 when Google launched its V8 JavaScript engine, and Firefox and Chrome managed to take back some of the market share from Internet Explorer.

The JavaScript language, in its current form, is considered to be a mature language and all features can generally be expected to behave the same way in all web browsers.




JavaScript is a programming language like C or python, but usually runs directly in our browsers.