Parsing is a fairly common word in the web developer’s vocabulary. We do it all the time. One immediately thinks of XML as something we parse regularly without batting an eyelid. As a PHP developer you might also parse an ini file with parse_ini_file, or parse a date string with strtotime. Whatever language you write, these tasks are easily achieved using either built-in functions or by installing other code libraries or extensions. Sometimes you may find yourself needing to parse something more bespoke, like say a postcode – you’ll either write a routine yourself, or do some googling for a neat algorithm someone out there has decided to share. – no problem.

A rod for my back

But what if you want to parse something really complex, like say – an entire JavaScript program. What if you can’t find a third party library that works for you? Well I tried to find one. I found some very promising projects. But they ranged from abandoned projects, to dodgy alpha releases, to ones that just plain didn’t work and with no documentation to help. The most serious looking projects were so sophisticated that I didn’t even have the knowledge to start using them. I decided, as I often do, that I need empowering with the knowledge to write my own parser should I need one for – well, whatever. Continue reading…