There are different levels at which you can learn about jQuery deferreds, and these each give a different perspective.
Next, there’s the official jQuery documentation for the
jQuery.when (which we’ll refer to as
now on), and the
.promise() function for DOM
element collections. The API documentation tells you what methods are
available, what their arguments are, methods that are deprecated or that
have changed between versions, etc. You’ll want to read the official
documentation closely and will probably return to it many times as you
become increasingly fluent with deferreds.
What’s missing is a higher-level discussion that explains the API and the dynamics of deferreds. That’s what we aim ...