问题
Can you help me to build a regex that matches a valid W3C HTML 4.01 id value?
According with W3C specs:
ID and NAME tokens must begin with a letter ([A-Za-z]) and may be followed by any number of letters, digits ([0-9]), hyphens ("-"), underscores ("_"), colons (":"), and periods (".").
回答1:
You can use this regex
^[a-zA-Z][\w:.-]*$
^ depicts the start of string
[a-zA-Z] matches an uppercase or lowercase letter
* matches the preceding character 1 to many times
\w is similar to [a-zA-Z\d_]
$ is the end of string
来源：https://stackoverflow.com/questions/14664860/allowed-html-4-01-id-values-regex