The meaning of the \b escape sequence inside a regular expression depends on its syntactic context: inside a character class, it matches the backspace character; outside of a character class, it matches a word boundary. This context dependency makes regular expressions hard to read, so the \b escape sequence should not be used inside character classes.

Replace \b in character classes with the semantically identical escape sequence \x08.

In the following example, the regular expression contains two uses of \b: in the first case, it matches a word boundary, in the second case it matches a backspace character.

To avoid mistaking the backspace character for the word boundary metacharacter, rewrite the regular expression as /\b[\t\x08]/.

  • Mozilla Developer Network: JavaScript Regular Expressions.
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