Your IDE should be catching any typos. But it's not about typos, it's about understanding the quirky nature of JS and knowing what things not to do. For instance, an inexperienced developer might try to use .sort() to sort an array of numbers. It wouldn't even occur to an experienced developer to try that since they know from vast past experience that it won't work (or, at least, won't do what the inexperience developer is thinking it might do).