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‫This is a really exciting lecture

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‫cause you're gonna learn how to read data from files,

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‫and also how to write data into files.

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‫And we already imported the built-in module

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‫that we need for that in the last lecture,

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‫and so let's now get rid of this code

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‫and start using the FS module.

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‫So we use fs.readfilesync, okay.

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‫And sync stands for synchronous,

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‫and you will start learning about synchronous

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‫and asynchronous right in the next video, okay.

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‫So this is the synchronous version of file reading.

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‫There is also an asynchronous version.

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‫So, the read file sync function takes two arguments.

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‫The first one is the path to the file that we're reading

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‫and then also the character encoded.

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‫So, first the path to the file,

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‫and the file is in the txt folder,

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‫and it is the input one.

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‫So, this text that I have here about the avocado

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‫is what we're gonna read into a variable.

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‫And I'm not sure if you're gonna be able

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‫to see this emoji here right on your operating system,

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‫but if you're on Windows 8 or Windows 10

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‫then that's probably going to work just fine.

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‫Okay, so we specified a path there,

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‫and there are multiple ways of doing that,

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‫but for now I'm gonna go with the simplest one.

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‫So, all I'm gonna do is set it in the /txt/input.txt.

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‫So again, we're starting at the home folder,

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‫which is basically the folder

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‫where the index.js file is located,

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‫so that's the dot in there,

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‫and then we move into the txt folder,

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‫and from there input.txt.

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‫Then here the second one we have

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‫to define the character encoding,

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‫which is utf8, usually,

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‫at least if you're just using English.

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‫Okay, and if you don't specify this,

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‫we get back something called a buffer, okay,

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‫and that's not really what we want.

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‫We really just want the text.

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‫And so, calling this function here will now read the data

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‫from the file and return it to us,

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‫and so we need save that somewhere

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‫and we put it into a variable.

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‫So let's say textIn because it's a more text input.

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‫Okay, and then let's log it to the console

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‫just to see if it works.

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‫Give it a second, and now we need to run this here again.

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‫So in the terminal, I can just use the up arrow

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‫to run the previous command.

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‫So here it is nodeindex.js again.

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‫Hit return, and let's see, and indeed here we go.

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‫So here is the content of that file.

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‫So, perfect.

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‫We now know how to read stuff from files.

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‫Congratulations.

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‫Okay, but we also want to know how to write to files.

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‫So let's create some new variable here with some more text,

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‫and then write it into a new file.

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‫So let's call that one textOut, so for output.

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‫And basically let's just write a string

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‫where we will then include this text in.

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‫I'm gonna be using a template string here,

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‫and at this point I'm gonna assume

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‫that you're kinda familiar with the es6 syntax, okay.

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‫So we already used const here,

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‫which is an es6 way of declaring variables instead of var,

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‫and now the template string, which is another es6 thing.

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‫So before the es6, if you wanted to add something

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‫to text in, you would have to use the plus operator.

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‫So let's say, "this is" and then space and then text in.

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‫Okay, so you would have to use the plus operator,

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‫but if it's a template string it's much easier.

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‫All we have to do is use the backticks, then some text,

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‫and then into this string you can

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‫very easily plug in the variable.

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‫So let's say, "This is what we know about the avocado."

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‫Then we use this syntax to input the variable, okay,

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‫and so basically inside of these curly braces here

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‫we can write any JavaScript that we want.

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‫So it's not just for plugging in variables straight away,

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‫we can also do a lot of calculations

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‫or any javaScript expression that we wanted in here.

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‫Now, let's say a new line character.

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‫So that's a new line, okay.

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‫And just to show you that we can actually use JavaScript

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‫inside of these curly braces here.

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‫So this dollar sign and then curly braces.

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‫So date, or actually date like this, dot now.

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‫Okay, so that is our string,

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‫which has this text here in together with the text

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‫that we read before from the variable.

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‫And so now let's write that to a new file.

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‫So again, we use the FS module,

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‫and this time, writeFileSync.

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‫Okay, and again we specify the path to the file,

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‫and we still want it in the txt folder,

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‫and we call it output.txt, okay.

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‫And now we have to actually specify

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‫what we want to write into that file, right,

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‫and tell us the text out variable.

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‫And this doesn't return anything meaningful

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‫until we don't save anything to any variable.

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‫All we do is to finally log something more to the console,

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‫like just informing if the file has been written.

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‫Okay, so let's test it out again.

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‫I'm gonna clear the console with command K.

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‫Hit the arrow up key, enter, and maybe you saw it.

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‫We here now have this new file called Output,

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‫and if I open it up, then you see,

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‫"This is what we know about the avocado,"

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‫which is what we wrote in the index.js,

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‫and then this is the text that came

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‫before from the input file, right.

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‫Then the new line that we created,

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‫and then created on this date basically.

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‫So this is date.now,

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‫so it's just a timestamp in milliseconds.

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‫All right, and this is how you read

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‫and write to and from files in Node.JS.