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