What is JavaScript?

JavaScript is a C-family language popularized by its wide use on the web.
It can be run on the browser. For example, click here to run a short script. JS code looks like this:

  var i = 1;
  var sum = 0;
  while (i < 1000)
   if (i % 3 == 0 || i % 5 == 0)
    sum = sum + i;
   i = i + 1;

I learned basic JS around 1998, tinkering with web pages. It wasn't until around 2004 that I truly realized the power of client-side code. Around that time, Google started auto-completing your search terms with XMLHttpRequest objects (XHR) in the background. We take this for granted now, but it felt very futuristic a mere 13 years ago. Now, we come to expect most SaaS websites to have rich web client experiences powered entirely by JavaScript, and on the back end, Node.js makes the language a full-stack powerhouse! Exciting times.