JS TutorialLesson 26Free preview

JS RegExp

This lesson is part of JavaScript · All levels

Summary

Regular expression (regex) is a character pattern for searching, checking, and changing text flexibly. In JavaScript, regex can be written literally as /learn/i or created with new RegExp(), and then used through method test, match, replace, and search. Flags like g (global) and i (case-insensitive) change matching behavior.

Key points

Literal regex: /pattern/flags, for example /^[a-z]+$/i
Test() return true/false, exec() check the details fit, replace() replace
The g-flag matches all the appearances, the flag I ignore the big little letters
Metacharacter like.*+?? and class characters [0-9] expand the pattern

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