Regular expression. How to make a custom condition

Question

I need to make the condition, that will grab the color codes in format #111; or #111111; from string str . If be more specifically, I need to grab only color codes with length: 3 or 6 after ' # ', any other codes need to be cut off.

 var str = "color: #3f3; background-color: #AA00ef; and: #abcd;"; var reg = /#.{3}?{6};/; // for now I'm getting an error: // Invalid regular expression: Nothing to repeat console.log(str.match(reg)); 

Answer 1

You could take a group with either three or six characters and a global flag.

 var str = "color: #3f3; background-color: #AA00ef; and: #abcd;", reg = /#(.{3}|.{6});/g; console.log(str.match(reg));