November 2006
Intermediate to advanced
977 pages
30h 42m
English
You want to classify values into broad categories.
Use a pattern that is similarly broad.
If you need to know whether values are empty or nonempty, or consist only of certain types of characters, the patterns listed in the following table may suffice:
| Pattern | Type of value the pattern matches |
|---|---|
/^$/
| Empty value |
/./
| Nonempty value |
/^\s*$/
| Whitespace, possibly empty |
/^\s+$/
| Nonempty whitespace |
/\S/
| Nonempty, and not just whitespace |
/^\d+$/
| Digits only, nonempty |
/^[a-z]+$/i
| Alphabetic characters only (case-insensitive), nonempty |
/^\w+$/
| Alphanumeric or underscore characters only, nonempty |
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