javascript - Why doesn't jQuery bomb if your selector object is invalid?

Question

Was recently using some code along the lines of

$("#divMenuContainer:visible").hide("explode");

However after some time spent trying to get it to work I realized my selector was referencing a div that didnt exist.

The result of the query was simply that it didn’t execute.

Obviously this is by design, could anyone explain the logic of why this design choice was made rather than raise some sort of exception?

Not trying to criticise just trying to understand.

Answer 1

Think of it as a query, which it is. You are asking for all "records" (DOM elements) that match your criteria. The result is a set of zero records.

It then loops over your zero records and applies the action to them. :)

If you did the same thing with SQL, or an array, it would behave the same way in most languages. A collection of zero records is not an error state.

var things = $("invalid selector");
$("p").text("The object is valid: " + things + " but has " + things.length + " elements.")

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<p></p>