I think you're remembering things from a Netscape perspective. For example you cite vbscript which was introduced a mere 8 months after Javascript (which was c

I think you're remembering things from a Netscape perspective. For example you cite vbscript which was introduced a mere 8 months after Javascript (which was called livescript at the time to match Netscape Livewire). So they were competing technologies and not either side ignoring a standard (MS to their credit quickly rushed jscript out when Javascript started to become dominant) (Edit: I was curious so I looked it up. Javascript was implemented by Netscape in Dec. '95. MS implemented Jscript in Aug 1996. Javascript was adopted as the ECMAScript standard in June '97) As for extensions I don't think you can consider those incompatibilities. Both sides were doing it. Yet on the Netscape side they were actually taking parts of the standard and not implementing them (which is something the open source team had to straighten out after it was turned over: http://oreilly.com/news/flanagan_1100.html http://oreilly.com/news/flanagan_1100.html) You can even find old IE reviews that point out Microsoft was implementing standards far quicker (like this one I found via wikipedia: http://www.pcpro.co.uk/reviews/peripherals/671/internet-explorer-4 http://www.pcpro.co.uk/reviews/peripherals/671/internet-expl...)