Canvas.toDataURL()未捕获TypeError:undefined不是函数

Question

我正在使用一个名为html2canvas的插件将我页面上的一些html转换为canvas元素.然后我想将该画布保存为图像.不幸的是,我一直遇到标题中的错误.我尝试过不同的变量名,不同的html等.但是仍然遇到同样的错误.这是我的代码(按下按钮时触发):

JS

function generate(){
        html2canvas($('#b2_1'), {
            onrendered: function(canvas) {
                canvas.setAttribute("id", "canvas");
                document.body.appendChild(canvas);
            }
        });//this all works, the canvas appears as expected

        var myCanvas = $(document).find('#canvas');
        myCanvas.css("margin-left", "50px");//this was to test I was selecting the right element, the canvas moves
        var myImg = myCanvas.toDataURL();//code breaks here
    }

Answer 1

好吧,我发现我的问题是我试图调用toDataURL()我的jQuery对象而不是我的canvas元素.为了解决这个问题我用过.get(0).完整代码如下:

function generate(){
        html2canvas($('#b2_1'), {
            onrendered: function(canvas) {
                canvas.setAttribute("id", "canvas");
                document.body.appendChild(canvas);
            }
        });//this all works, the canvas appears as expected

        var myCanvas = $(document).find('#canvas');
        myCanvas.css("margin-left", "50px");
        var myImg = myCanvas.get(0).toDataURL();//have to get the canvas element from the jquery object
    }