Week 9 Assignment 3

by Larry Adams

HTML

<h3>Practice Set, Week 9, Keyboard Events</h3>

<p>This page contains a box with a "puck" in it. The javascript contains functions that will move the puck in each of four directions. Your task is to write an event handler that will respond to the keyboard - specifically, to allow the user to use the arrow keys to move the puck around.</p>
<p>You can attach an event handler to the window object, and have a conditional to see which key was pressed. The <a href="http://jsfiddle.net/cscie3/j1uLsvay/">keyCode utility</a> we referred to in Week 9, lesson 3 of the course may be helpful to you.</p>
<p>Also, when running your code in JSFiddle, you will have to give this HTML output frame focus (by clicking on it once) for your code to capture keyboard activity. </p>
<p>Hint - all you have to do is listen for keydown or keyup, and depending on which arrow key was pressed, call the appropriate function. </p>
<div id="container">
    <div id="output"></div>
    <div id="puck"></div>
</div>

CSS

#container{
    height: 200px;
    width: 400px;
    border: 1px solid black;
    background-color: #dddddd;
}
#puck{
    border: 1px solid red;
    height: 20px;
    width: 20px;
    background-color: red;
    position:relative;
    top: 90px;
    left: 190px;
}

JavaScript

/*

Source Stakeoverflow: http://stackoverflow.com/questions/23585320/how-to-move-object-with-keyboard-in-javascript

jsfiddle source: http://jsfiddle.net/gabs/paw4X/

*/


// Add your event handler here to listen for keyboard
//   activity and call the functions below as needed.
// I used the conditional statement to control the keys and puck.

var container = document.getElementById("container");

// initial location of the puck, and step size
var step = 4;
var top = 90;
var left = 190;

// utility functions that will move the puck
var puck = document.getElementById("puck");

document.addEventListener('keydown', function(event) {
//left
if(event.keyCode == 37) {
	 left -= step;
    puck.style.left = left + "px";
}
//top
else if(event.keyCode == 38) {
	top -= step;
    puck.style.top = top + "px";
}
//right
else if(event.keyCode == 39) {
	left += step;
    puck.style.left = left + "px";
}
//bottom
else if(event.keyCode == 40) {
	top += step;
    puck.style.top = top + "px";
}
});

/*
function mvup(){
    top -= step;
    puck.style.top = top + "px";
}
function mvdown(){
    top += step;
    puck.style.top = top + "px";
}
function mvleft(){
    left -= step;
    puck.style.left = left + "px";
}
function mvright(){
    left += step;
    puck.style.left = left + "px";
}

*/