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In this video we'll recap what you've learned with callbacks.
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[MUSIC]
0:00
Well done.
0:04
Callbacks can be challenging but
they're a powerful tool in asynchronous,
0:05
event based programming.
0:09
They're everywhere in JavaScript.
0:11
I encourage you to take the course
again if you're still having problems
0:13
surrounding callbacks.
0:17
The second time through,
there may be some more a ha moments.
0:18
Let's recap on some of
the things that you've learned.
0:22
Functions are often referred to as
first class objects in JavaScript.
0:25
All this means is that a reference
to the function can be passed around
0:29
just like any other variable.
0:33
Remember, a callback
function is like any other.
0:35
Instead of call by you in the code it's
being triggered by a system event.
0:39
In the case of setTimeout,
0:44
the callback is invoked after a delay
which is supplied as a second argument.
0:46
Remember, you don't include parenthesis
when you pass in the name of
0:51
the function since that would
invoke the function immediately.
0:55
Callbacks can be expressed as an anonymous
function too or an arrow function.
1:00
Some callbacks can have
arguments passed in.
1:06
In the case of the addEventListener,
1:09
the callback can have a single
argument passed in, the event object.
1:12
Callbacks are everywhere in JavaScript,
whether you stay in the front-end, or
1:17
move over to the back-end with Node.js.
1:21
You'll encounter them in all of
your JavaScript developer life.
1:23
I hope you enjoyed this course, and
until next time, keep on coding.
1:27
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