Canvas.toDataURL（）未捕获TypeError：undefined不是函数 [英] Canvas.toDataURL() Uncaught TypeError: undefined is not a function

问题描述

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）：

I'm using a plugin called html2canvas to convert some html on my page into a canvas element. I then want to save that canvas as an image. Unfortunately I keep encountering the error in the title. I have tried with different variable names, with different html, etc. But keep encountering the same error. Here is my code (triggered on a button click):

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
    }

推荐答案

好的，我发现我的问题是我试图在我的jQuery对象而不是我的canvas元素上调用 toDataURL（）。为了解决这个问题，我使用了 .get（0）。完整代码如下：

Ok, I found my problem was I was trying to call toDataURL() on my jQuery object rather than my canvas element. To fix this I used .get(0). Full code below:

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
    }

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