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 can I do that? I'm trying the following which isn't working:
^[(http)(https)]://
9 Answers
Your use of [] is incorrect -- note that [] denotes a character class and will therefore only ever match one character. The expression [(http)(https)] translates to "match a (, an h, a t, a t, a p, a ), or an s." (Duplicate characters are ignored.)
Try this:
^https?://
If you really want to use alternation, use this syntax instead:
^(http|https)://
8 Comments
Steve Tauber
As a PHP input string: $regex = '/^(https?:\/\/)';
Axi
Steve, I think you missed a / at the end: $regex = '/^(https?:\/\/)/';
jeffkee
Just in case some nut accidentally uppercases the http, $regex = '/^(https?:\/\/)/i';
Shafizadeh
You forgot to escape / using \. So it would be
^https?:\/\/. Am I right?
cdhowie
@Shafizadeh
/ is not a special character in regular expressions, only in languages where / is used to notate a literal regular expression. For example, it is not necessary to escape / in regular expressions when using C#, because C# regular expressions are expressed (in part) as string literals. Nor do you need them in, say, Perl (when using an alternate delimiter as in m#^https?://#). So to directly address your comment: (a) No, I did not forget to escape anything. (b) You will need to escape whatever characters are treated specially in your language of choice. |
Case insensitive:
var re = new RegExp("^(http|https)://", "i");
var str = "My String";
var match = re.test(str);
Comments
^https?://
You might have to escape the forward slashes though, depending on context.
Comments
^https?:\/\/(.*) where (.*) is match everything else after https://
Comments
This should work
^(http|https)://
Comments
^ for start of the string pattern,
? for allowing 0 or 1 time repeat. ie., s? s can exist 1 time or no need to exist at all.
/ is a special character in regex so it needs to be escaped by a backslash \/
/^https?:\/\//.test('https://www.bbc.co.uk/sport/cricket'); // true
/^https?:\/\//.test('http://www.bbc.co.uk/sport/cricket'); // true
/^https?:\/\//.test('ftp://www.bbc.co.uk/sport/cricket'); // false
Comments
(http|https)?:\/\/(\S+)
This works for me
Not a regex specialist, but i will try to explain the awnser.
(http|https) : Parenthesis indicates a capture group, "I" a OR statement.
\/\/ : "\" allows special characters, such as "/"
(\S+) : Anything that is not whitespace until the next whitespace
1 Comment
darclander
Could you provide more detail how it works? And use `` for code in order to make the answer more clear.
This will work for URL encoded strings too.
^(https?)(:\/\/|(\%3A%2F%2F))
Comments
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/ididn'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>
[]. It will mach one character that is either(,),h,t,t,pors. I.e. it would matchs://but notht://orx://./^x/vsindexOf(x) == 0). "starts with" style approaches may have less overhead, but I suspect it rarely matters -- choose what is the cleanest, which very well may be:x.StartWith("http://") || x.StartsWith("https://")-- but do so out of code clarity, not an attempt to improve performance unless justified with analysis and requirements :-)