Basics
Regular expressions are typically formatted as /<rules>/<flags>. Often people will drop the slashes and flags for brevity. We’ll get into the details of flags in a later chapter.
Let’s start with the regex /p/g. For now, please take the g flag for granted.
/p/g[RegExr] [Visual]- 1 match
pancakep
- 3 matches
pineappleppp
- 2 matches
applepp
- 0 matches
mango - 0 matches
Plum
As we can see, /p/g matches all lowercase p characters.
Note
Regular expressions are case-sensitive by default.
Instances of the regex pattern found in an input string are termed “matches”.
/pp/g[RegExr] [Visual]- 1 match
applepp
- 1 match
pineapplepp
- 1 match
happinesspp
- 2 matches
sipping apple juicepppp
- 0 matches
papaya