- We can anchor regular expressions to word boundaries.
- That is the start or the end of a word.
\b –> Word boundary (start/end of word)\B –> Not a word boundary.
- This one is not used regularly.
- Reference a position, not an actual character.
- Word boundary exists before the first word character.
- Before the first word character in the string.
- After the last word character in the string.
- Between a word character and a non-word character.
- Word chracters: [A-Za-z0-9_]
- When we change from something in the above character set, to something that is not within the character set, that is a word boundary.
- An example, we have
/\b\w+\b/ which finds four matches in “This is a test.”
- There is a word boundary before the “T”.
- Boundary before the “t” and the “.”
/\b\w+\b/ matches all of “abc_123”, but only part of “top-notch”.
- Word characters do not include hyphens.
/\bNew\bYork\b/ does not match “New York”.
- There is a boundary after the “w” before the “ “.
- There is a second boundary after the “ “ before the “Y”.
- Cannot substitute a word boundary instead of a space.
/\bNew\b \bYork\b/ matches “New York”.
/\B\w+\B/ find two matches in “This is a test.” (“hi” and “es”)/e\b/
- This matches the letter “e” at the end of all words that end with “e”.
- Similarly with
/\ba\b/, this matches “a” on its own.
- Allows to make your regex more efficient and faster.
- Another example is
/\b\w+s\b/
- This is looking for a word that ends in “s”.
+ is 1 or more times.- The above will try to match “We picked apples.”