The World Wide Web was originally a bunch of pages linked together by hyperlinks. Soon people wanted more interaction and so Netscape (an early browser vendor) asked Brendan Eich to develop a new language for their Navigator browser. This needed to be done quickly because of the intense competition between Netscape and Microsoft to be first to market, and Eich managed to create a prototype language in just ten days.

In order to do this, he borrowed various elements from other languages, including AWK, Java, Perl, Scheme, Hyper Talk, and Self. The new language was originally called Live Script, but was hastily rebranded as JavaScript so that it could benefit from the publicity that the Sun Microsystem’s Java language was attracting at the time.

This name has often caused some unfortunate confusion, with JavaScript often thought of as a lighter version of Java; the two languages are unrelated, although JavaScript does share some syntax with Java.

JavaScript made its debut in version 2 of Netscape’s Navigator browser in 1995. The following year, Microsoft reverse-engineered JavaScript to create their own version, called JScript to avoid copyright issues with Sun Microsystems who owned the Java trademark and had licensed it to Netscape. JScript shipped with version 3 of the Internet Explorer browser and was almost identical to JavaScript―it even included all the same bugs and quirks―but did have some extra Internet Explorer-only features.

Microsoft included another scripting language called VBScript with Internet Explorer at the same time, although this never really caught on. JavaScript (and JScript) was immediately popular. It had a low barrier to entry and was relatively easy to learn, which meant an explosion in its usage making web pages dynamic and more interactive.

Unfortunately, its low barrier was also a curse as it meant that people could write snippets of code without much understanding of what they were actually doing. Code could be easily copied and pasted and was often used incorrectly, leading to lots of poor code examples appearing all over the Web. JavaScript was also frequently used to create annoying pop-up adverts and for browser sniffing (the process of detecting which browser was being used to view a web page), and it started to gain a negative reputation.

Netscape and Sun Microsystems decided to standardize the language along with the help of the European Computer Manufacturers Association, who would host the standard. This standardized language was called ECMAScript, again, to avoid infringing on Sun’s Java trademark. This caused even more confusion, but eventually ECMAScript was used to refer to the specification, and JavaScript was (and still is) used to refer to the language itself.

The ECMAScript standard can be difficult to interpret in places, so the implementations of JavaScript can vary in assorted JavaScript engines. This is why some web browsers behave differently when running JavaScript programs.