javascript - Extract ip address from a string using regex -

 var r = "\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b"; //http://www.regular-expressions.info/examples.html  var = "http://www.example.com/landing.aspx?referrer=10.11.12.13";  var t = a.match(r); //expecting ip address result gets null 

the above code extract ip address string. fails so. kindly advice fails.

you have defined r string, initialize regular expression.

var r = /\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b/; 

var r = /\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b/; //http://www.regular-expressions.info/examples.html    var = "http://www.example.com/landing.aspx?referrer=10.11.12.13";    var t = a.match(r);  alert(t[0])