What’s the use of the [\b] backspace regex?

by

While all the others are right in general (that \b is a word boundary), \b does mean backspace inside character classes:

[\b]

This will indeed match a backspace character. It’s just an ASCII control character that can appear in text (ASCII code 8, or 10 in octal). I suppose it’s mostly used for legacy reasons, to add diacritical marks (e.g. you could do a, backspace, ´, to get á). Today these have been mostly replaced by Unicode combining marks.

How a string containing a backspace will ultimately look depends on the software that renders it. Consoles will probably still move the cursor back and overwrite what was there if the backspace is followed by new other characters. To see this, fire up an interactive scripting console (like node.js if you want to try it in JavaScript), and run

> console.log("abc\b\bdef")
adef

Note that, had you omitted def, you’d just get abc, because the backspace itself does not erase anything. It only moves the cursor back.

On the other hand, your browser might just ignore it in an input field. For instance, check out a Unicode converter, enter the JavaScript input abc\b\bdef in the bottom left input, hit “convert”, and the “Characters” output will not have the bc erased.

By the way \b being a backspace in character classes is not unique to JavaScript, but interpreted this way in most regex flavors.

Further reading:

More Related Contents:

  1. Split a string between special characters [closed]
  2. Javascript: Decimals still being allowed in regex check for numbers [duplicate]
  3. Not able to get Regular Expression in javascript
  4. Regex to replace multiple spaces with a single space
  5. Regex to match all instances not inside quotes
  6. Regex to check whether a string contains only numbers [duplicate]
  7. Regular expression which matches a pattern, or is an empty string
  8. Template literal inside of the RegEx
  9. JavaScript regex pattern concatenate with variable
  10. javascript regular expression to check for IP addresses
  11. How can I replace a regex substring match in Javascript?
  12. replace all occurrences in a string [duplicate]
  13. Passing regex modifier options to RegExp object
  14. How to access object property with invalid characters
  15. How to ignore acute accent in a javascript regex match?
  16. Regex that can match empty string is breaking the javascript regex engine
  17. JavaScript replace/regex
  18. Regular Expression for formatting numbers in JavaScript
  19. Regular Expression – Extract subdomain & domain
  20. Regex for Umlaut
  21. Switch statement for string matching in JavaScript
  22. JavaScript text between double quotes
  23. Use of capture groups in String.split() [duplicate]
  24. Converting latitude and longitude to decimal values
  25. Remove all occurrences except last?
  26. What is the best way to parse html in google apps script
  27. What is the advantage of unroll the loop compared to shorter regex notation with quantified alternatives?
  28. Match all URLs in string and return in array in JavaScript
  29. Regex.prototype.exec returns null on second iteration of the search [duplicate]
  30. Part of String Case Insensitive in JavaScript Regex (?i) option not working

Leave a Comment