我正在嘗試將 html5canvas 轉換為圖像，并希望再次在頁面中加載該圖像，但它不起作用。window.onload = function() {    }  function myFunction() {    var v = document.getElementById("mTextArea").value;    document.getElementById("wow").innerHTML = v;    html2canvas(document.getElementById("imagewrap"), {      onrendered: function(canvas) {        canvas.className = "html2canvas";        var image = canvas.toDataURL("image/png");<====        document.getElementById("img_prev").innerHTML = image;<====      },      useCORS: true    });  }