BASICS

Case sensitivity

Patterns are case-sensitive by default. The i flag turns that off.

By default error does not match "Error". Case matters, character by character.

Most engines let you attach flags that change how the whole pattern behaves. The i flag means ignore case, so error then matches error, Error, and ERROR. From this lesson on you have a flags input next to the pattern.

i ignore case for the whole pattern

g global - find all matches, not just the first (always on here)

There are more flags, each covered later: m (multiline anchors), s (dotAll), u/v (unicode), y (sticky). Full list: MDN: flags.

EXERCISE

Match every form of the word error, regardless of case.

/ /

Error: file not found

must match: "Error"

the error was logged twice

must match: "error"

ERROR ERROR

must match: "ERROR" "ERROR"

no problems here

must match nothing

ALL LESSONS PREV: LITERAL TEXT TRY IT IN THE TESTER REGEX CHEATSHEET

NEXT: THE DOT