if you want to ,是if you want to have a look around it.的缩写.
省略了to的话,意思表达不清了.也可以说成 Go ahead if you like.
祝进步.为啥意思会表达不清啊？if you want to动词+宾语。如果是 if you want, 要接to动词+宾语一般是to跟前面的。want to 是想干什么。