Introduction to HTML5 Canvas - HTML5 Canvas - page 21

Using the document Object to Reference the Canvas Element
in JavaScript

We will now make use of the DOM to reference the <canvas> we defined in HTML. Recall
that the document object represents every element of an HTML page after it has loaded.

We need a reference to the Canvas object so that we will know where to display the Canvas
API calls we will make from JavaScript.

First, wewill define anewvariable named theCanvas that will holdthe reference tothe Can-
vas object.

Next, we retrieve a reference to canvasOne by calling the getElementById() function of
document , and passing the name canvasOne , which we defined as the id of the <canvas> tag
we created in the HTML page:

var var theCanvas = document . getElementById ( "canvasOne" );