Array comparison? - regex

Question

I am making a function that takes in an example and an ip address. For ex.
compare('192.168.*','192.168.0.42');
The asterix indicates that the following parts of ip can be anything. The function returns true or false based on if the example and ip is a match. I tried this kind of solution.
var compare = function(example, ip){
var ex = example.split(".");
var ip = ip.split(".");
var t = 0;
for(var i=0; i<4; i++){
if(ex[i] == ip[i] || ex[i] == "*" || typeof ex[i] === 'undefined' && ex[i-1] == "*"){
t++
if(t==4){
return true
}
}else{
return false;
}
}
}
What are the main advantages of using regular expression over this solution? What would be the best regular expression to do this?

Answer 1

How about checking if they are not equal then just return false?
var compare = function(example, ip){
// You should have some basic IP validations here for both example and ip.
var ex = example.split(".");
var ip = ip.split(".");
for(var i=0; i<ex.length; i++){
if(ex[i]=='*')
break;
if(ex[i]!=ip[i])
return false;
}
return true;
}
alert(compare('333.321.*','333.321.345.765'));
alert(compare('333.322.*','333.321.345.765'));
alert(compare('333.321.345.*','333.321.345.765'));

Answer 2

This goes way better with regular expressions. Try this:
function compare(example, ip) {
var regexp = new RegExp('^' + example.replace(/\./g, '\\.').replace(/\*/g, '.*'));
return regexp.test(ip);
}
compare('192.168.*', '192.168.0.42'); // => true
compare('192.167.*', '192.168.0.42'); // => false
What this does is, it translates your pattern to an regular expression. Regular expressions are extremely powerful in matching string. It also covers cases like this:
compare('192.168.*.42', '192.168.1.42'); // => true
compare('192.167.*.42', '192.168.1.43'); // => false