Hey!.

OK.

Another fun fact about our next speaker: If you haven't seen his profile picture for the

conference, definitely check it out.

It's actually him playing onstage at metal fest in Peru, when he did a South American

tour with the thrash metal band.

Lots of talent.

So next we have playing Pokémon with Samuel Agnew.

Guess I should have checked this before.

I see someone coming forward.

[applause]

Is there any way I can get like something where I don't need to use my hands?

>> Unless I could, could, like, one-hand live code.

>> AUDIENCE: Technically you just did.

>> Yeah, I guess I did.

There's my talk.

Dang, though, so this thing is not a thing.

OK, I don't need to be coding until a couple minutes into my talk so I might as well get

started.

How's it going JSConf, a company called Twilio pays me to build goofy hacks and about them

and I flew in from New York City the other day, and speaking of JavaScript developers

from New York, I want to give a quick shout to by buddy speaking in the other track.

You should watch it on YouTube later because he also organization a meetup called Queens

JS which is one of my favorite ones and sometimes I convince my employer to give them money.

This talk is going to be more of a fun one than a serious.

It's the last session and I know towards the ends of conferences attention spans start

wane, so I figured what could be more fun than playing Pokémon with a bunch of JavaScript

developers.

I'm running Pokémon red version which is a game I played a ton as a kid.

And I have the Windows version of this emulator running, even though I'm on a Mac and the

reason for that is there are a lot of old game emulators where the Windows versions

of them have developer tools, because people still make real games for these old systems,

and for some reason or other, most of those developers use Windows, so one of the features

that this emulator has that I'm going to be using for my talk is scripting functionality

so we can run lui scripts and we can control the memory of the game and button input and

stuff like that.

I'm being mic'd up.

Cool. [laughter]

So what we're going to do is we're going to write a Lewis script that interacts with a

node.js express server sitting behind a Twilio phone number and I'm going to have you all

text a Twilio phone number to tell me what buttons to press in the game and the Node

app and the script are going to communicate with each other.

Testing, can you hear me?

AUDIENCE: Yes!

Sweet, awesome, so this might sound kind of familiar to to some of you.

If you about five years ago, there was a twitch.tv livestream but instead of a human being playing

it, it was everyone watching the stream typing in the chat which buttons would be pressed

and when you have 80,000 people playing the same game controlling it at the same time,

things get pretty interesting.

So when I found out that these emulators had scripting, I guess because I work for Twilio,

I was like, whoa, wouldn't it be cool if you could do that with text messages, too?

And I it turns the Lua scripting thing is really popular in the speed scripting community.

Where people try to write scripts to complete games in the most efficient way possible.

This documentation seems pretty bare boneses so I've actually been following this other

emulator's documentation.

Turns out all these old game console emulate y they have the exact same Lua API I guess

because they're all open source and once one implemented it the other ones were like, cool,

gonna copy and paste that.

You can do stuff like read and write bytes to the game's memory, like the RAM and ROM

and that kind of stuff.

I'm going to have this Twilio phone number set up so that I can programmatically control

T so whenever you send a text message to this phone number and it's a 760 phone number which

I think is an area code around here.

So whenever you send a text to that number Twilio is going to send a post address to

this address right here, which is basically a tunnel to a port on my local machine that

my Node express app is going to be listening on.

That app does not exist yet so we'll get to that later.

If you text this number right now, literally nothing will happen because it will be dropped

on the floor because the code doesn't exist.

I'll show it on the screen later so you don't have to copy it down right now.

Anyway, let's get into the basics of how to write code for this Game Boy emulator.

I'm going to do a Hello World thing, you might have seen on this, I have my Twitter handle

up on the Game Boy emulator.

My Twitter is sagnewshreds,

I'm going to say hello, JSConf with a smiley face, and I'm going to save that and I'm going

to stop this other script from happening.

And I'm going to go find this Lua script on my computer in my talks folder in the JSConf

folder and I'm going to run that and it says, hello, JSConf cool, we've run some Lua.

But it disappeared.

And the reason is it's only running once.

We can repeatedly print this on every frame if we want it to stay.

And for that we need to write an infinite loop.

Because infinite loops rule, right?

We write those all the time.

Because this emulator, the whole environment in there is single threaded this will actually

stop the game from even playing.

So this emu object gives you a function where you can control the frames so you can advance

to the next frame.

This way our infinite loop is pretty much taking over the run time of the game so that

each iteration of this loop is going to be one frame of the game.

So all this code will execute on each frame so I'm going to advance to the next frame

at the end of each loop and going to restart that and now the hello JSConf is going to

stay there.

Now I'm going to write some useful stuff.

So what we want to do is this Lua script is going to communicate with our Node.js stuff.

I know this is JSConf and I'm writing Lua.

I'm not much of a Lua developer.

I don't know how many of you in this room consider yourselves Lua developers, but I'm

not particularly.

So I'm going to write some code to communicate with that Node.js and we're going to do something

technologically advanced here.

Really complicated stuff.

We're going to communicate by reading and writing to text files.

Yeah, so on each frame I'm going to read from a file called button.txt, to see if a button

was pressed.

So I'm going to write some utility function, so I'm going to write a function that can

read a file and then I'm going to open that file.

If I can type correctly.

Cool.

So I'm going to open that file name with the read flag and then I'm going to check to see

if that file actually exists, so if it's nil, then I'm going to set the input to be that

file, and then I'm going to create a variable called content and read the contents of that

file into it.

And then I'm going to close the file, because you always gotta close something you open.

You gotta finish what you started, right?

And then I'm going to return the content of the file which should just be a string of

whatever was in the file.

And next I'm going to write a quick function to press a button in the game.

So this is going to take a button, just like the text of a button, like A, B, start, select,

up, down, something like that.

And the way the joy pad API works in this Lua scripting is that it takes a table of

buttons, like a key value kind of thing, like a JavaScript object or a Python dictionary

and it takes the button name and true or false for whether that button is being pressed or

not.

So I'm just going to create an input table here.

And empty one, and I'm going to set whatever button we're trying to press equal to true.

And then I'm going to call the joy pad.set function, and this is actually kind of interesting

right here.

One of the idiosyncrasies of this is there's only one or two controllers, but I guess because

they copy and pasted for the consoles, you still have to give it the button input.

So unless you're giving the link input, there's only one player, so player 1 is going to have

this input table and I'm going to go down to this infinite loop and we're going to say

for each frame of the game I'm going to check to see if there is anything in button.txt,

so I'm going to create a variable that is going to read the contents of button.txt and

if the button is nil.

Press the button, pretty simple, right?

So I'm going to put a message out to say I'm pressing the button.

As I said, I'm not much of a Lua developer, so Lua string concatenation is just two dots.

So if that looked a little funky to you, that's what that is, that is just string concatenation.

So I'm going to avoid duplicates like if you send A to the text message thing and then

it writes the button to that file, I just want to press the button once, I don't want

to keep pressing on each frame repeatedly.

Like if you want to press the button twice, you'll.

It's going to return nil and button is going to be nil, so this won't be executed, but

speaking of pressing buttons for multiple frames, that's another thing I want to address.

So you are all human beings and when you're playing a video game, you're not playing as

fast as machine would, so when you press a button on a Game Boy you're at least holding

the button down for a solid portion of a second.

So we're going to want to press it for a certain number of frames.

Let's say 5.

Which is still not a long time, but long enough for it to register and this is the syntax

for a foreloop in Lua.

But I want to make sure I advance the frame again after each iteration of the loop.

So we're done with the talk using a language no one writes, or at I guess some of you do.

I guess technically do.

Because I'm writing it right now.

But first I'm going to reload this Pokémon.lua script.

Now I'm going to write the letter A, capital letter A in this text file and if I didn't

mess anything up, when I go back to the emulator, it should be pretsing the A button and as

you see, it's on this menu screen, so if it works this should go to the screen where I

select a new game.

Pressing A. -- I mean I guess it said it was pressing A. Oh, there we go.

Maybe five frames wasn't enough, actually.

But we'll see.

So the Lua code works, that's great.

I'm glad to hear that.

Now I'm going to open up a saved state that I have, because later on once we're actually

playing this, I don't want to have us to sit through Professor Oak telling us all what

to do.

All right, time to go now, I'm going to write some JavaScript finally.

So I'm going to open a file called index.js and I'm going to build a quick express app

so for a lot of people who are already familiar with backend Node development this will seem

pretty straightforward for you for those of you who aren't familiar with backend node.js

development, I guess this will be a good little Kickstarter.

So first, going to require the FS module, because you know, writing to files, gotta

use the file system for that.

Also going to require express, because it is the web framework that I'm using, and I'm

going to grab body parser, because I'm going to need to deal with the body of a post request,

because when you send the text message, Twilio sends the post request representing the message

and I need to get stuff in the body of that post request to access what the text of that

message is.

So body.parser and now I need to use the Twilio API.

The Twilio node module and I'm going to grab the messaging response object from that so

this will generate the twiml for me.

Twiml being the Twilio SMS.

My web app is going to have to respond with these XML tags, particularly the messaging

response one, saying hey, respond to this message with a text message and no one wants

to write XML by hand, I don't so I'm going to do this.

Cool, I'm going to create my app object and I'm going to make an array of valid Game Boy

buttons that you can text.

They're also the start and select buttons on the Game Boy, but I'm not going to use

that one, because that opens up the opportunity for you all to troll me by spamming the start

menu and that's not fun, so I'm not going to let you do that, at all.

Next I want to make sure I'm using the body parsing middleware, can't forget that so when

I get the URL encoded post body I'll actually be able to use it.

Gonna write that real quick.