You can just add the times together
function goodTimes() {
var arr = [];
$.each(arguments, function() {
$.each(this.split(':'), function(i) {
arr[i] = arr[i] ? arr[i] + (+this) : +this;
});
})
return arr.map(function(n) {
return n < 10 ? '0'+n : n;
}).join(':');
}