Regex: To Escape or Not to Escape Hyphens?

When working with regular expressions, the use of hyphens can cause confusion. Hyphens can be used to represent a range of characters, such as [a-z] to match any lowercase letter. However, hyphens can also be used as literal characters, such as in the word "co-worker". So, when should hyphens be escaped in regular expressions?

Hyphens in Character Classes

When using hyphens within character classes, it is important to escape them if they are meant to be interpreted as a literal character. For example, to match the string "co-worker" using a regular expression, the hyphen must be escaped like this: /co-worker/. Otherwise, the regular expression would interpret the hyphen as a range character and the expression would not match.

Hyphens Outside of Character Classes

If a hyphen is not within a character class, it does not need to be escaped. It will be interpreted as a literal character. For example, to match the string "email-address" using a regular expression, the hyphen does not need to be escaped like this: /email-address/.

Conclusion

To summarize, hyphens should be escaped in regular expressions when they are meant to be interpreted as a literal character within a character class. Outside of character classes, hyphens do not need to be escaped. Remembering these rules will help ensure that your regular expressions match the intended strings.