Question

How can I test a string if it begins with “files/” and/or ends with “.js”?

Examples:

• test/test2/test.html –> true
• files/test2/test.html –> false
• test/test2/test .js –> false
• files/test2/test .js –> false

So far I have this regular expression: (^(?!files\/)).*?((?!\.js)$)

This works for “files/” but not for “.js”.

Edit:
Sorry for the misunderstanding. The string should only match if a string does NOT start with “files/” and does NOT end with “.js”.

Answer 1

Your last negative should be a look behind not a look ahead, At the point of the test you’ve already read the .js

^(?!files\/).*(?<!\.js)$