Question

I would like javascript detect the source of the image and take action regarding it is full URL or not with REGEX

Example Code:

var source = 'http://test.com/';
if( [if var source starting with http:// ] ){ // Regex conditional
    // do something
}else{
    // // something
}

How to do that with Javascript regex?

Thank you…

Answer 1

Here you go if you are adamant on Regex:

^https?:\/\/.*$

Javascript code to test here:

  var re = /^https?:\/\/.*$/;
  var sourcestring = "source string to match with pattern";
  var matches = re.exec(sourcestring);
  for (var i=0; i<matches.length; i++) {
    alert("matches["+i+"] = " + matches[i]);
  }

For your code:

var source = 'http://test.com/';
var pattern = /^https?:\/\/.*$/;
if(null != pattern.exec(source))
{ 
    // Regex conditional
    // do something
}
else
{
    // // something
}

---

But please note that this ONLY checks the first part of the URL, which may not necessarily mean that the rest of the string conforms to an URL. For e.g., your source string can be something like “http://^&#*@%.IAmABadUrl.com” which is not a valid URL if sent unencoded.
More about whats allowed in an URL on the IETF website:

Thus, only alphanumerics, the special characters “$-_.+!*'(),”, and
reserved characters used for their reserved purposes may be used
unencoded within a URL.