On Feb 19, 10:56 am, Alexandre Plennevaux <aplennev...@gmail.com>
wrote:
> thanks a lot. But why did they made it so complex? do we really need
> the granularity to differenciate between "undefined", null, 0, "" and
> false ?
Yes, they are all have their uses in different circumstances.
For example, host methods like getElementById return null if they
can't find the element they're after. It lets you know that the
method ran OK, it just didn't find the element. Others, like
getElementsByTagName, always return a collection. If it's empty, a
test like:
if (nodeCollection) {...}
will evaluate to true, however since there are no elements in the
collection, it's length with be zero so:
if (nodeCollection.length) {...}
will evaluate to false (and true if there is at least one node in the
collection).
Javascript was intended to be a simple, easy to learn language so it
has lots of features that are designed to make programming easier -
e.g. lose typing and automatic conversion of primitives to objects
where required. Those same features raise other issues when you dig
into the detail.
--
Rob
