Javascript: How to get string between ( and ) using Regular Expressions

I wanted to get a string that was surrounded with round brackets "(" and ")"

Here's how:

var str = "hi (1111) bye";
var re = /\((.*?)\)/;
var matches = str.match(re); 
if (matches) { 
 var submatch = matches[1]; 
}

Then when you print submatch, you get 1111