Introduction to JavaScript

From the very beginning

Emily Y Leung
5 min readJul 31


Field notes while going through the JavaScript Roadmap

Photo by Luca Bravo on Unsplash

What is JavaScript?

  • JavaScript is one of the core technologies used in the World Wide Web (alongside HTML and CSS)
  • It is a scripting language typically used to make webpages interactive by programming the behavior of web pages — sliders, alerts, click interactions, popups, etc.
  • Modern web browsers support JavaScript through built-in engines
  • JavaScript was originally created for the browser. But since the creation of NodeJS in 2009, this runtime engine allows JavaScript to be run outside of the browser. Now we can build real-time, scalable web applications, servers, build desktop applications with Electron and create mobile apps with React Native, etc.
  • It supports object-oriented, imperative and delcarative (e.g. functional programming) styles

History of JavaScript

  • On 25th December 1990, Sir Tim Berners-Lee introduced the first web browser — WorldWideWeb. It was created on the NeXT computer system in Switzerland — around the same time he created the first web server
  • In December 1991, Al Gore invented the internet. He introduced the Gore bill which funded the first browser — Mosaic — developed by Marc Andreessen and Eric Bina at the University of Illinois
  • In January 1993, Mosaic was published for UNIX systems. It was the first web browser that introduced the Internet. No JavaScript existed at this point — only the DOM which had yet to be standardised
  • In 1993, Andreessen graduated and co-founded Netscape in California. With Netscape Navigator holding over 80% of the browser market share within the first few years, Andreessen noticed that browsers would need to become more dynamic and required a new language to do this
  • JavaScript was created by Brendan Eich of Netscape in 1995. Originally it was named Mocha, then later renamed to LiveScript (in September 1995). In 1996, after its release, NetScape decided to rename it to JavaScript (to capitalize on the Java community) even though there was no correlation to Java (while its syntax slightly resembled it)