Sometimes I feel like the difference between a junior, intermediate, and senior developers is that the junior hasn&#x27;t yet figured out how to use regexps, the intermediate dev has, and the senior dev has figured out not to.<p>I kid, but...really.  The number of times I&#x27;ve seen people burnt by non-trivial regexps in production code is absurd.<p>&quot;Oh, I need to mangle this CSV that&#x27;s in the wrong format&quot;?  Sure, write a one-off regexp.<p>&quot;Hm, there might be a security vulnerability in this URL parameter, I need some way to filter out bad inputs...&quot;  Oh <i>hell</i> no.<p>Literally two weeks ago I tracked down a crazy bug to a regexp someone had written to try and correct mistyped email addresses in a signup form (?!) that deleted &quot;invalid&quot; characters.  Like a &quot;+&quot;.  So many facepalms for one short line of code...