Yes you can. It's a bit deeper than you might be used to;

var sizeWidth = ctx.canvas.clientWidth;

var sizeHeight = ctx.canvas.clientHeight;



var scaleWidth = sizeWidth/100;

var scaleHeight = sizeHeight/100;

A common example of the Canvas context object;

> CanvasRenderingContext2D

    canvas: HTMLCanvasElement

    constructor: CanvasRenderingContext2DConstructor

    fillStyle: #000000

    font: 10px sans-serif

    globalAlpha: 1

    globalCompositeOperation: source-over

    lineCap: butt

    lineJoin: miter

    lineWidth: 1

    miterLimit: 10

    shadowBlur: 0

    shadowColor: rgba(0, 0, 0, 0)

    shadowOffsetX: 0

    shadowOffsetY: 0

    strokeStyle: #000000

    textAlign: start

    textBaseline: alphabetic

    webkitBackingStorePixelRatio: 1

    webkitLineDash: Array[0]

    webkitLineDashOffset: 0

    __proto__: CanvasRenderingContext2DPrototype

And the HTMLCanvasElement inside it;

> canvas: HTMLCanvasElement

    accessKey: 

    attributes: NamedNodeMap

    baseURI: http://fiddle.jshell.net/_display/

    childElementCount: 0

    childNodes: NodeList[0]

    children: HTMLCollection[0]

    classList: DOMTokenList

    className: 

    clientHeight: 150

    clientLeft: 1

    clientTop: 1

    clientWidth: 300

    constructor: HTMLCanvasElementConstructor

    contentEditable: inherit

    dataset: DOMStringMap

    dir: 

    draggable: false

    firstChild: null

    firstElementChild: null

    height: 150

    hidden: false

    id: c1

    innerHTML: 

    innerText: 

    isContentEditable: false

    lang: 

    lastChild: null

    lastElementChild: null

    localName: canvas

    namespaceURI: http://www.w3.org/1999/xhtml

    nextElementSibling: HTMLCanvasElement

    nextSibling: Text

    nodeName: CANVAS

    nodeType: 1

    nodeValue: null

    offsetHeight: 152

    offsetLeft: 8

    offsetParent: HTMLBodyElement

    offsetTop: 8

    offsetWidth: 302

    onabort: null

    onbeforecopy: null

    onbeforecut: null

    onbeforepaste: null

    onblur: null

    onchange: null

    onclick: null

    oncontextmenu: null

    oncopy: null

    oncut: null

    ondblclick: null

    ondrag: null

    ondragend: null

    ondragenter: null

    ondragleave: null

    ondragover: null

    ondragstart: null

    ondrop: null

    onerror: null

    onfocus: null

    oninput: null

    oninvalid: null

    onkeydown: null

    onkeypress: null

    onkeyup: null

    onload: null

    onmousedown: null

    onmousemove: null

    onmouseout: null

    onmouseover: null

    onmouseup: null

    onmousewheel: null

    onpaste: null

    onreset: null

    onscroll: null

    onsearch: null

    onselect: null

    onselectstart: null

    onsubmit: null

    onwebkitfullscreenchange: null

    onwebkitfullscreenerror: null

    outerHTML: <canvas id=c1></canvas>

    outerText: 

    ownerDocument: HTMLDocument

    parentElement: HTMLBodyElement

    parentNode: HTMLBodyElement

    prefix: null

    previousElementSibling: null

    previousSibling: Text

    scrollHeight: 150

    scrollLeft: 0

    scrollTop: 0

    scrollWidth: 300

    spellcheck: true

    style: CSSStyleDeclaration

    tabIndex: -1

    tagName: CANVAS

    textContent: 

    title: 

    translate: true

    webkitRegionOverflow: undefined

    webkitdropzone: 

    width: 300

    __proto__: HTMLCanvasElementPrototype