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A Javascript/HTML5 tutorial – Part 1 building a basic Text Adventure
Introduction
I come from the age when text adventures were serious fun, ZORK and Hitchhikers guide to the galaxy were two of my favourite text adventures. OK so maybe the golden age of the text adventure is still stuck in the 1980’s but I still remember those glory days. So the game I am building is certainly not up there in the same territory as ZORK but I hope you can see the sort of cool things you can do with Js/Jquery and HTML 5.
The game is pretty simple use the N,S,E and W to move around the dungeon and a few other useful commands. Search for the Dragon and if you have the right weapon and equipment you may be able to kill it. If you use a mobile browser you should see some buttons that make life a little easier than using a little virtual keyboard.
Here is the game : http://domssite.com/search/
Who is this for
Anyone interested in learning Javascript, jQuery and HTML 5.
How to use the tutorial
Its not an ordinary tutorial so you need to accept that first. Its based on reading and understanding code and code comments. I have used heaps of comments throughout the code to explain whats going on. There’s a lot of Arrays, so you’ll see lots of code using arrays and its not a bad starting place for working with js structures. The whole tutorial is 1 single file – whilst a single large file is not the best way to build large web apps – its not a bad approach showing everything in one file.
The first part of the puzzle : the HTML
<!--Text Adventure : Search for the Dragon --> <!--***************************************** Text Adventure - A JS/JQuery/HTML5 Tutorial by comments The game : Standard Text Aventure where you can move from room to room, collecting items and killing monsters Goal is to get to the final room of the dungeon and kill the dragon Start in room 1 Monsters dont move Monsters can be killed by certain weapons Should work in both mobile and non-mobile browsers History : 0.1 Initial version before Hilary's comments/advice ***************************************** --> <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Search</title> <script src="Scripts/jquery-1.7.1.min.js"></script> <link href="Content/Site.css" rel="stylesheet" /> </head> <body> <div class="content"> <style> </style> <div id="screenContainer"> <div id="display"> <div id="input"> <form> <!--Screen Title--> <h1>Search... </h1> <!--Screen Sub-Title--> <h3>For a Dragon...Text Adventure Game by @DungeonBard </h3> <div id="GameOverDiv"> </div> <div id="GameDiv"> <!--The following div is hidden or shown depending on if its a non-mobile browser--> <div id="Keyboard"> <label>Command:</label> <input type="text" name="userInput" class="buttonMod" id="userInput" /> </div> <!--The following div is hidden or shown depending on if its a mobile browser--> <div id="controllers"> <!--We use a table for the simple alignment of the buttons--> <table> <tr> <td></td> <td> <input type='button' class='button' value='N' title="North" style="left: 200px" /></td> <td></td> </tr> <tr> <td> <input type='button' class='button' value='W' title="West" /></td> <td></td> <td> <input type='button' class='button' value='E' title="East" /></td> </tr> <tr> <td></td> <td> <input type='button' class='button' value='S' title="South" /></td> <td></td> </tr> <tr> <td></td> <td></td> <td></td> </tr> <tr> <td> <input type='button' class='button' value='P' title="Pickup" /></td> <td> <input type='button' class='button' value='A' title="About" /></td> <td> <input type='button' class='button' value='?' title="Help" /></td> </tr> </table> </div> </div> <div id="output"></div> </form> </div> </div> </div> </body> </html>
Part 2 : the Javascript
<script type="text/javascript">
//Our main js code called by Jquery on doc ready
$(document).ready(function () {
//game variables
var message, //screen message to display
hits = 10, //hit points for the player
lightLevel = 100, //current light level
currentRoom = 0, //initial room
exitRoom = 31, //final room of the dungeon
IsGameOver = false; //Maintain the state of the game
IsOgreAlive = true, //Stores the state of the Ogre - Alive/Dead
IsDragonAlive = true; //this is the gameover state
//All the commands we use in the game
var gameWords = new Array("HELP", "Find/earch", "N-orth", "S-outh", "W-est", "E-east','A-About");
//All the rooms in the game
var rooms = new Array("Dungeon Entrance", "Corridor of uncertainty", 'Ancient old cavern', "Great Cavern", "Underground River", "Stream", 'Dungeon Stream', "Dungeon Pool",
"Large Cavern", "Rough Tunnell", "Long Tunnell", "Dark Room", "Dark Room", "Cold Room", "Old Tunnel", "Cold Room",
"Old Cavern", "Short Corridor", "Short Corridor", "Grey Room", "Green Room", "Old Prison Cell", "Underground River",
"Large Cavern", "Rough Tunnell", "Long Tunnell", "Dark Room", "Dark Room", "Cold Room", "Old Tunnel", "Dragons Room");
//Each exit relates to the index ie. Exits[0] SE which means rooms[0] the long path has two exits on the South and East. If we look
//down to the //Movement Code section you can see how we work out which rooms are connected to which
var exits = new Array("E", "SWE", "WE", "SWE", "WE", "WE", "SWE", "WS",
"NSE", "SE", "WE", "NW", "SE", "W", "SNE", "NSW",
"NS", "NS", "SE", "WE", "NWE", "SWE", "WS", "N",
"N", "NWE", "NWE", "WE", "WE", "NW", "NE", "W");
//All out game objects
var GameObjects = new Array('', "Painting", "Knife", "Wand of Firebolts", "Goblet", "Wand of Wind", "Coins", "Helmet", "Candle", "Torch", "Iron Shield", "Armour", "Oil", "AXE", "ROPE", "BOAT", "AEROSOL", "CANDLE", "KEY");
//Inventory array Contains all the things you can carry
var inventory = new Array();
inventory[0] = 2; //lets start our player off with a knife
//location of game objects - these objects relate to a array index - so Object[1] the Painting is located
//in rooms[2] the small garden - 999 indicates out of play
var objectLocations = [999, 1, 999, 3, 4, 5, 6, 7, 8, 10, 11, 15, 14, 12, 18, 19, 16, 17, 9]
//This function detects if the browser if a mobile - you'll see when we call this we apply the
function isMobile() {
return navigator.userAgent.match(/Android/i) || navigator.userAgent.match(/BlackBerry/i) || navigator.userAgent.match(/iPhone|iPad|iPod/i)
|| navigator.userAgent.match(/Opera Mini/i) || navigator.userAgent.match(/IEMobile/i);
}
//The next line checks for a mobile browser and if it find st it will hide the buttons or hide the text box
if (isMobile()) {
//hide the text box - we dont need that for a mobile browser as its hard to use mobile keyboard for lots of commands
$("#Keyboard").hide();
} else {
//hide the buttons as we don't want that for the normal web experience
$('#controllers').hide();
//jquery command to force the textbox to take focus
$("#userInput").focus();
}
//javascript function to pickup the object in this room
var pickup = function (roomIndex) {
var itemIndex;
if (objectLocations[roomIndex] > 0 && objectLocations[roomIndex] < 100) {
itemIndex = objectLocations[roomIndex];
inventory[inventory.length] = itemIndex;
objectLocations[roomIndex] = 999;
alert(objectLocations[roomIndex]);
}
}
//This function loops through the object location array and returns
function getObjectForRoom(currentRoom) {
var roomIndex = -1;
for (var i = 0; i < objectLocations.length ; i++) {
if (objectLocations[i] == currentRoom)
roomIndex = i;
}
return roomIndex
}
//This is a method/function that shows the game screen. If we look in deatil at this function we can see that
//it uses another function DisplayText to show each line of the screen.
function DisplayGameScreen() {
//clear the output div
$display.empty();
//Display the screen output text - note this does not include the buttons
DisplayText("You are now in the :");
DisplayText(rooms[currentRoom]);
DisplayText("Exits: " + ShowAdjacentRooms(exits[currentRoom]) + "<br />");
DisplayText('DB:' + currentRoom + 'Light:' + lightLevel + "Hits:" + hits);
if (getObjectForRoom(currentRoom) != -1) {
var index = getObjectForRoom(currentRoom);
DisplayText("You can see " + GameObjects[index]);
}
//If there is something in our inventory then display it
if (inventory.length > 0) {
DisplayText("You are carrying: ");
for (var i = 0; i < inventory.length ; i++) {
DisplayText("-" + GameObjects[inventory[i]]);
}
}
if (message != null)
DisplayText(message.toUpperCase());
//Game over code
if (IsDragonAlive) {
$('#GameOverDiv').hide();
$('#GameDiv').show();
}
else {
$('#GameOverDiv').show();
$('#GameDiv').hide();
}
message = "What?";
}
//Replaces the indexOf js function as i have found it doesn't always work for me!!!!!!!!
function checkIndex(issFullArray, issToCheck) {
for (i = 0; i < issFullArray.length; i++) {
if (issFullArray[i] == issToCheck) {
return true;
}
}
return false;
}
//Uses the text for a room to build a string that shows which rooms are next to the current room
function ShowAdjacentRooms(e) {
var newExits = "";
if (e != null) {
for (i = 0; i < e.length; i++) {
if (i === e.length - 1) {
newExits += e.substring(i, i + 1);
} else if (i === e.length - 2) {
newExits += e.substring(i, i + 1) + " & ";
} else {
newExits += e.substring(i, i + 1) + ", ";
}
}
}
return newExits;
}
//Simple js function to display a line of text
function DisplayText(text) {
$display.html($display.html().toString() + text + "<br>");
}
//Each round we call this function to do all the main game processing
function ProcessGameRound(command) {
//Remove any spaces from the command text
trimCommand = $.trim(command);
//Process command takes the players action
ProcessCommand(command);
//NOw that we have taken the players logic we need to activate the main game room logic
if (currentRoom == 10 && OgreAlive) {
//if you are fighting the ogre and you have the spells
if (checkIndex(inventory, 3)) {
message += "\<br\>YOU attack the ogre with magic spells and kill him!";
OgreAlive = false;
}
else {
message += "\<br\>Ogre attacks you!";
hits--;
}
}
//If you are in the final room and the dragon is still alive
if (currentRoom == 31 && IsDragonAlive) {
//if you are fighting the dragon and you have the oil, burning torch
if (checkIndex(inventory, 5) && checkIndex(inventory, 9) && checkIndex(inventory, 12)) {
message += "\<br\>You attack the dragon with oil, burning torch and the wand of Wind - It creates and kill him!";
IsDragonAlive = false; //End Game
}
else {
message += "\<br\>The dragon attacks you with firebreath and kills you!";
hits = 0;
}
}
if (currentRoom == 25) {
//if you are fighting the gas room burning torch
if (checkIndex(inventory, 10)) {
message += "\<br\>The gas in the room is ignited by the torch - You become a human BBQ and die!";
hits = 0;
}
}
DisplayGameScreen();
}
function ProcessCommand(command) {
var direction = command;
message = "OK";
switch (command) {
//Movement Code
case "N":
if (exits[currentRoom].indexOf(direction) > -1)
currentRoom -= 8;
else
message = "Can't move there";
break;
case "S":
if (exits[currentRoom].indexOf(direction) > -1)
currentRoom += 8;
else
message = "Can't move there";
break;
case "E":
if (exits[currentRoom].indexOf(direction) > -1)
currentRoom++;
else
message = "Can't move there";
break;
case "W":
if (exits[currentRoom].indexOf(direction) > -1)
currentRoom--;
else
message = "Can't move there";
break;
//End of Movement Code
case "P":
pickup(currentRoom);
break
case "A":
if (exits[currentRoom].indexOf(direction) > -1)
message = "About ... Game built for #1GAM, LD48 (failed) and my friend Hilary";
break
case "?":
message = "The following commands are valid: N S E W P A ?";
break
}
}
//JQuery selector that handles the form submit -
$('#input form').submit(function (evt) {
ProcessGameRound($('#userInput').val().toUpperCase());
$('#userInput').val('');
evt.preventDefault();
});
//sets the output div to the display variable
$display = $('#output');
// This is jQuery selector that picks up an event from the button - in this case we look at the value of the button ie. its text and use that
//to call the same function as we would call from the equivalent keyboard command
$(".button").click(function (e) {
switch (this.value) {
case "N":
ProcessGameRound('N');
break;
case "S":
ProcessGameRound('S');
break;
case "E":
ProcessGameRound('E');
break;
case "W":
ProcessGameRound('W');
break;
case "F":
ProcessGameRound('F');
break;
case "P":
pickup(currentRoom);
break;
case "A":
ProcessGameRound('A');
break;
}
});
DisplayGameScreen();
});
</script>
Are the bugs
Yep – Totally , lots that the point – we’ll start cleaning them up in the next version
Next
I’ll add in a series of improvements in version 2 of this game.
Source Control link
7drl reviews part one RODNEY
Just doing some reviews this is the first game i have come across by slash and its seriously cool – great old school rogue-like with very cool IRC feature where I got to chat with the dev – SLASH. Its an excellent game with classic rogue-like features and cool shading effects!!! Also for HTML/JS people this is a great example of what you can do (also includes Websockets – SLASH told me).
Not sure how many I’ll get to but this was a great start.
Cool game http://slashware.net/rodney/
Great podcast on Javascript
Free HTML 5 and js ebook
Free html5 and js resources
Doms Code 