Short Answer: No But.... knowledge is power.

I'm a web developer and i find any Regular Expression i generally need has already been written for me. However i have had problems with copying and pasting and not realizing what it was doing or not, which is a danger of copying and pasting ANYTHING.

One example: An email regex i copied and pasted didn't allow for a period or plus in an email which is allowed in the email address spec. In fact many people use gmail with [email protected] so that it becomes easy to filter 'sitename' should they choose to spam.