js導出div爲圖片

<div id="tbl_exception">
            <p style=" color: chartreuse;">你的名字<span style='color:aqua; text-shadow:0 0 2px blue;'>aaa</span></p>
        </div>
        <a id="Down">
            <img id="img" />
        </a>
        <button id="btn_screen">點擊</button>

<script type="text/javascript" src="js/html2canvas.js"></script>
$("#btn_screen").on("click", function() {
                html2canvas($("#tbl_exception"), {
                    height: $("#tbl_exception").outerHeight() + 20,
                    onrendered: function(canvas) {
                        var url = canvas.toDataURL();
                        $("#img").attr("src", url);
                        $("#Down").attr("href", url);

                    }
                });
            });

html2canvas

圖片下載：a標籤的download屬性