Extracting for URL from string using regex

I want to extract the first valid URL in a string, which can be anywhere between characters and whitespace

I have tried with the following

...
urlRegex: /^http[s]?:\/\/.*?\/([a-zA-Z-_]+).*$/,

...
var input = event.target.value // <--- some string;
var url   = input.match(this.urlRegex)[0];

Problem is url returns the whole string when it finds a url, instead of returning just the part of the string matching the regex

How can this be achieved?