function getParams(input){
var matches = [];
input.replace(/({+)([^}]+)(}+)/g,function(orig,lb,txt,rb){
if (lb.length === rb.length)
matches.push(txt);
});
return matches;
}
var string = "<div>{{foo}} and {{{bar}}} and {{{{hahahaahahahahahaha}}}}</div>";
document.write(getParams(string));