Regex to test if string begins with http:// or https://

Question

I\'m trying to set a regexp which will check the start of a string, and if it contains either http:// or https:// it should match it.

How c

Answer 1

Making this case insensitive wasn't working in asp.net so I just specified each of the letters.

Here's what I had to do to get it working in an asp.net RegularExpressionValidator:

[Hh][Tt][Tt][Pp][Ss]?://(.*)

Notes:

• (?i) and using /whatever/i didn't work probably because javascript hasn't brought in all case sensitive functionality
• Originally had ^ at beginning but it didn't matter, but the (.*) did (Expression didn't work without (.*) but did work without ^)
• Didn't need to escape the // though might be a good idea.

Here's the full RegularExpressionValidator if you need it:

<asp:RegularExpressionValidator ID="revURLHeaderEdit" runat="server" 
    ControlToValidate="txtURLHeaderEdit" 
    ValidationExpression="[Hh][Tt][Tt][Pp][Ss]?://(.*)"
    ErrorMessage="URL should begin with http:// or https://" >
</asp:RegularExpressionValidator>

Answer 2

Case insensitive:

var re = new RegExp("^(http|https)://", "i");
var str = "My String";
var match = re.test(str);

Answer 3

This will work for URL encoded strings too.

^(https?)(:\/\/|(\%3A%2F%2F))