invalid escape in pattern HTML/Javascript

Question

I am trying to make an input field that uses a pattern to check if the input is a valid windows file path. The pattern i have is

/^(?:[\w]\:|\\)(\\[a-zA-Z_\-\s0-9\.()~!@#$%^&=+';,{}\[\]]+)+\.(exe)$/g

however when putting this into the pattern attribute of an input field it says (in console)

Pattern attribute value ^(?:[\w]:|\)(\[a-zA-Z_-\s0-9.()~!@#$%^&=+';,{}[]]+)+.(exe)$ is not a valid regular expression: Uncaught SyntaxError: Invalid regular expression: /^(?:[\w]:|\)(\[a-zA-Z_-\s0-9.()~!@#$%^&=+';,{}[]]+)+.(exe)$/: Invalid escape

I have tried several different ways of writing this but none seem to work.

Answer 1

You only need to escape the characters in the character class that must be escaped otherwise, you will always get this error.

Use

pattern="(?:\w:|\\)(\\[\w\s.()~!@#$%^&=+';,{}[\]-]+)+\.exe"

See the JSFiddle

Details:

• The hyphen must be at the end of the character class
• The ] inside the character class must be escaped
• The [ and . must not be escaped
• The : must never be esacaped, it is never a special character
• [a-zA-Z0-9_] = \w
• The pattern is always anchored by default, you need no ^ and $ anchors.