Regular Expressions – Mastering Lookahead and Lookbehind

March 16, 2018


Very useful examples on a pretty complex and powerful feature that allows you to: Asserts that what is immediately after or before the current position is or is not X.

I am not sure if they mention performance issue but keep that in mind when dealing with complex regex. Even big sites have had issues relating to regex consuming CPU like crazy in some tricky input.

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