We often say this:
The most difficult things to understand in the world are Taoist priests’ ghost charms and doctors’ prescriptions
In fact, we still need Add a sentence:
The most difficult things in the world to understand are Taoist priests' ghost symbols, doctors' prescriptions and programmers' regular expressions.
Let’s first look at what a regular expression looks like:
/^a-z@([a-z0-9][-_]?[a-z0-9]+)+[.][a-z]{2,3}([.][a-z]{2})?$/i
Haha, I feel heartbroken just looking at it. Let me state in advance, don’t be intimidated, you will find that it is not that difficult after you study it.
Regular expression means we have seen it often before. It is mainly used in the following places:
Let’s study this chapter and first learn and understand the basic techniques that regular expressions need to master bit by bit.