getContext(2d)来自动态添加的画布和jquery

这里有点新手,可能超出了我的深度但是我循环了一些导入的xml并附加一个带有div的容器,然后用画布附加它,然后我试图绘制到那个画布.我得到的只是’getContext()不是一个函数’任何指导感激不尽

var newCanvas = 
    $('<canvas/>',{'class':'cnvsClass'},{'id': 'theCanvas'})
    .width(215)
    .height(217);


$("#innerWrapper")
    .append($('<div/>',{'class': 'wrapper'})
        .append($(newCanvas)));



// Have tried  $('<canvas/>',$('.cnvsClass'),$("#theCanvas")
// I've added [0] after the SELEctor but all I get is 
// TypeError: $(...).getContext is not a function
var ctx = $("#theCanvas").getContext("2d");

var image = new Image();
image.src = "AtlasSheet.png";  
$(imagE).load(function() {
    ctx.drawImage(image,830,1165,215,217,217);    
});

var ctx = $("#theCanvas").get(0).getContext("2d");