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All right, and once we have covered why it's so important to use the asynchronous approach now, of

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course, let's clean up our F a sink.

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So instead of using these nested callbacks, let's see a nice pattern.

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And as a side note, if you want to see the code that we wrote in a previous video and the one we were

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about to write and the files are located in two async patterns folder, so I'll close everything for

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now.

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And then back in objets, I can remember, like I said, if you want to access that code, it is sending

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in the two async patterns folder and we'll simply start by recreating the read file setup where I'm

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going to go with CONST.

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I'm right away accessing that from the filesystem module and I'll set it equal to require, of course,

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on that file system.

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All right, that's awesome.

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We know that it is a asynchronous so we need to set it up with three parameters.

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We go with read file and then we would want to pass in the path first.

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So again, since I mean, I'm just going to be looking for the content online forward slash and then

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first the next the file.

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We already created before then we have encoding.

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So comma.

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And then again we're going to go with UTF eight and the last one is going to be that callback where

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the first value is the error and then the second one is the data that we're getting back.

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OK.

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So once the file system responds, then, of course we invoke this callback and instead of that callback,

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we have our logic.

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So if there's going to be an error for the time being, I will just return.

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OK, so, um, then if I have the data, I'll set it up else.

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So say here comes a log on there.

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Of course.

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And we shouldn't be surprised if we see in a console.

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Hello.

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This is a first text file because we already covered the setup.

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Right.

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So we're passing the path we pass in the encoding and then we set up the callback.

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Now the problem starts.

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If we would want to perform multiple actions, if I want to read two files and then, for example,

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write one.

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Correct.

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So what would be a better solution?

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Well, a better solution would be turning this into a promise and then eventually we'll set up a sync

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away.

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Now, please keep in mind that the only reason why we'll type out the promise stuff is because I would

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want you to understand what is happening behind the scenes.

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But don't worry, throughout the course, we'll just stick with async and avoid syntax.

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And essentially, you won't have to worry about what is happening behind the scenes.

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But the first example, yes, I want you to understand everything in detail.

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So what we could do is create a new function.

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And we can just say Consed, and then I'll call this get text now this text will take a bath since I

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want to read two files and then eventually write one as well, just like we did here.

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And of course the goal here is to showcase how we can make the code in the face a sink.

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At least that's how I called my file much cleaner and more readable.

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So I'm going to pass in the path I'm on.

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One I would want to return from this function is a promise.

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So we go return new promise and that in the promise object, what we need to pass in is another callback

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function.

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So we pass and the callback function and in here we pass in two more functions, one for resolve and

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then one for project.

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And then once I have set up both of these parameters.

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Now, of course, what I want is to move the read file and place it inside of the promised one.

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OK, so once we place it here, first of all, notice here how I'm passing in the path.

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So of course I can change this one around so I can say path I'm on.

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The encoding stays the same as well as the callback for inside of the callback.

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Once I have access to resolve and reject what I could simply say that if there is an error, I will

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spit back the error.

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So say reject an error.

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And if everything goes great now, of course, let's go with a resolve and mine will pass in the data.

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And once we have the setup, what's really cool that now I can invoke get text and this is going to

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return a promise and then of course we can change that then and catch so below the text I can go and

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get text.

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And of course we're looking for the path, so we still would need to use that and then forward slash

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and then content, of course, and first the act.

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So that's the path.

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And then like I said, we are returning a promise so we can change that then.

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And of course here I can have the result and I'll just cancel it for now or assault.

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And then I can also change that sketch here.

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I'm passing in the error.

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So again, we console Target and we simply would want to see the error.

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I save it.

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And beautiful.

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Again, in Arkansas, I have hello, this is first text file, so I know that it worked and also if

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I change the path, so if I make my path incorrect, we should see in the console the error where,

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of course, node cannot find the file.

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So if that works now, of course, we can take a look at how we can make it even cleaner by setting

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up a sink or.