Possible Duplicate:
Regular expression to match string not containing a word?
How can I invert a regular expression in JavaScript?
Say I have the regex foo123. How do I match everything that is not foo123?
Use negative lookahead for this.
(?!foo123).+
matches any string except foo123
If you want to match empty string also, use (?!foo123).*
In your case (according to the comment) the required regex is (?!P[0-9]{1,}).+.
It matches P and 123, but not P123.
来源：https://stackoverflow.com/questions/14682905/how-to-negate-regex