Regular Expressions

Lookarounds

Lookarounds are useful when you want to match (or exclude) results based on what comes before or after the current position.

Name	Expression	Description
Lookahead	`(?=pattern)`	Asserts that the string following the current position is “pattern”
Negative Lookahead	`(?!pattern)`	Asserts that the string following the current position is not “pattern”
Lookbehind	`(?<=pattern)`	Asserts that the string preceding the current position is “pattern”
Negative Lookbehind	`(?<!pattern)`	Asserts that the string preceding the current position is not “pattern”

Updated October 2020