What is the need for caret (^) and dollar symbol ($) in regular expression?

Javascript RegExp() allows you to specify a multi-line mode (m) which changes the behavior of ^ and $.

^ represents the start of the current line in multi-line mode, otherwise the start of the string

$ represents the end of the current line in multi-line mode, otherwise the end of the string

For example: this allows you to match something like semicolons at the end of a line where the next line starts with "var" /;$\n\s*var/m

Fast regexen also need an "anchor" point, somewhere to start it's search somewhere in the string. These characters tell the Regex engine where to start looking and generally reduce the number of backtracks, making your Regex much, much faster in many cases.

NOTE: This knowledge came from Nicolas Zakas's High Performance Javascript

Conclusion: You should use them!

^ represents the start of the input string.

$ represents the end.

You don't actually have to use them at the start and end. You can use em anywhere =) Regex is fun (and confusing). They don't represent a character. They represent the start and end.

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