Replacing with groups

In a replacement string, `$1` inserts what group 1 captured and $& the whole match. Note the sigil flips: inside the pattern a backreference is \1, but in the replacement string it is $1. Swap "Doe, Jane" into "Jane Doe": pattern (\w+), (\w+), replacement $2 $1.

This lesson switches the playground to replace mode: pattern on the left, replacement on the right. Replacement strings are plain text apart from the $ references.

More replacement tokens: $& is the whole match, $<name> a named group, and $$ a literal dollar sign. MDN: specifying a string as the replacement.