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Welcome back in the previous video we saw some good use cases for call and apply.

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We saw how to explicitly set the context of the key word this and pass arguments to the function that

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is being altered by call or apply in the case of call arguments are passed as comma separated values

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but with Apply arguments are passed as values in an array.

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Bind works just like call but instead of calling the function right away it returns a function definition

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with a keyword this set to the value of this arc.

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So when is bind useful one common use case is when we do not know all of the arguments that will be

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passed to a function which means we don't want to invoke the function right away.

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We just want to return a new function with some of the parameters set.

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We call this partial application.

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In the example below we can see that bind is returning a function definition to us.

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So we still need an extra set of parentheses to call the function.

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What's neat about bind is that we do not need to know all the parameters to the function.

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When we bind it we only need to know what we want the value of the keyword this to be.

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It's a little bit tricky.

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So make sure to pause the video and type the examples on the slide and play around with partial application

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.

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Another very common use case of BIND is to set the context of the keyword.

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This for a function that will be called at a later point in time.

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Very commonly This happens when dealing with asynchronous code or code that doesn't run line by line

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before you take a look at these examples.

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Let's quickly review the asynchronous set timeout method.

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So timeout is a method on the window object that's used to execute a function once after a specified

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amount of time.

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Remember that said timeout is the method on the window object.

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That's something we're going to need to remember for a later example.

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The first parameter to set timeout is a function to be executed.

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And the second parameter is the amount of time in milliseconds to wait before executing the function

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.

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Let's code a quick example and cancelled out Lague Hello world.

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After 20 seconds I'm going to call set timeout and pass in a function that will counseled out loud Hello

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world after 20 seconds.

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Now that I've called this I can actually do other things like define new variables or continue running

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code.

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This is what we mean by asynchronous.

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Our code is not blocked while we wait 20 seconds and we can do other things while we wait.

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There goes our council that blog.

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Great.

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And the next video will come back to talking about the keyword this.

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And take a look at a pretty tricky example.

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