javascript - Regular expression for browser Url

Question

I am new to JavaScript

i need a regular expression which

allows both of this forms

for example :

1. http://www.google.com
2. www.google.com

Answer 1

var url_pattern = new RegExp("((ftp|http|https)(://))?([a-zA-Z0-9]+[.]{1}){2}[a-zA-z0-9]+(/{1}[a-zA-Z0-9]+)*/?", "i");

return url_pattern.test(url);