元素不会在javaScript中作为子元素添加

Question

我正在尝试使用HTML2Canvas将我的元素转换为PNG文件，稍后将该PNG转换为PDF。为此我有功能：

function makeImage(){
    var $printSection = createPrintSection();
    addElement(document.getElementById("accordion"),$printSection);
    addElement(document.getElementById("fullHistory"),$printSection);
    return $printSection;
}

如果没有名为printSection的div，则createPrintSection创建div：

function createPrintSection(){
    var $printSection = document.getElementById("printSection");
    if (!$printSection){
        var $printSection = document.createElement("div");
        $printSection.id = "printSection";
        document.body.appendChild($printSection);
    }
    $printSection.innerHTML = "";
    return $printSection;
}

现在addelement会：

function addElement(elem,parent) {
    var domClone = elem.cloneNode(true);
    parent.appendChild(domClone);
}

如果我在给它一个值之后放入console.log（domClone），它表明它已成功完成它。但是，它不会被添加到它的父子节点（$ printSection - 执行console.log（$ printSection）将返回一个空div到控制台）。有什么想法可能会发生吗？

这是我的完整代码：

function tryThis(){
    var $printSection = makeImage();
    console.log($printSection);
    html2canvas($printSection, {
        onrendered: function(canvas) {         
            var imgData = canvas.toDataURL(
                'image/png');
            console.log(imgData);
            var doc = new jsPDF('p', 'mm');
            doc.addImage(imgData, 'PNG', 10, 10);
            var name = document.getElementById("tabelinimi").textContent;
            if (name.length < 2){
                name = "nameless";
            }
            var deit = datemaker();
            var stringB = name+"_table_"+deit+".pdf";
            doc.save(stringB);
        }
    });
    removePrintSection()
}

function makeImage(){
    var printSection = createPrintSection();
    console.log(printSection);
    addElement(document.getElementById("accordion"),printSection);
    addElement(document.getElementById("fullHistory"),printSection);
    return printSection;
}

function datemaker(){
    var today = new Date();
    var dd = today.getDate();
    var mm = today.getMonth()+1; //January is 0!
    var yyyy = today.getFullYear();

    if(dd<10) {
        dd='0'+dd
    } 

    if(mm<10) {
        mm='0'+mm
    } 

    today = mm+'.'+dd+'.'+yyyy;
    return today;
}

function createPrintSection(){
    var $printSection = document.getElementById("printSection");
    if (!$printSection){
        var $printSection = document.createElement("div");
        $printSection.id = "printSection";
        document.body.appendChild($printSection);
    }
    $printSection.innerHTML = "";
    return $printSection;
}

function addElement(elem,parent) {
    var domClone = elem.cloneNode(true);
    domClone.id = elem.id+"_copy";
    console.log("DomClone: ");
    console.log(domClone);
    parent.appendChild(domClone);
    console.log("Parent: ");
    console.log(parent);
}

function removePrintSection(){
    var $printSection = document.getElementById("printSection");
    if (!$printSection){
        return;
    }
    else{
        $printSection.innerHTML = "";
    }
}

这是来自控制台的图片摘录：

我通过点击HTML按钮调出tryThis（）。