The Essential Guide to HTML5

CHAPTER 3

Code Explanation

} Close clause

if (nbally < inboxboundy) { Is the y value less than the top boundary?

nbally = inboxboundy; If so, set the y value to be exactly the boundary

ballvy = -ballvy; Change the vertical displacement

} Close clause

ballx = nballx; Set the x position to nballx

bally = nbally; Set the y position to nbally

} Close moveandcheck function

function change() { Start of change function

ballvx = Number(f.hv.value); Convert input to number and assign to ballvx

ballvy = Number(f.vv.value); Convert input to number and assign to ballvy

return false; Returnfalse to make sure there isn't a page reload

} Close function

Close script
Close head
Start body element. Set up call to init function

<canvas id="canvas" width=

"400" height="300">

Start of canvas element

Your browser doesn't support the

HTML5 element canvas.

Message for non-compliant browsers

Close canvas element

Line break