如何在javascript html中添加父/子节点

您好，在下面的代码中，我有一个用于建筑的树状视图结构。树状视图中包含一个建筑和不同的楼层。 现在在那栋楼里我有4层楼。假设我想在这幢楼里再加一层楼。那么怎么做呢

然后，如何为下面的代码将子节点添加到特定的父节点。单击“添加”按钮后，我可以将其添加到父节点或子节点下的位置

错误：

morris.js:86 Uncaught Error: Graph container element not found
    at Area.Grid [as constructor] (morris.js:86)
    at Area.Line [as constructor] (morris.js:824)
    at new Area (morris.js:1451)
    at Object.Area (morris.js:1444)
    at dashboard-ecommerce.js:202
chartist.min.js:8 Uncaught TypeError: Cannot read property 'querySelectorAll' of null
    at Object.c.createSvg (chartist.min.js:8)
    at f.e [as createChart] (chartist.min.js:9)
    at f.h (chartist.min.js:8)
chartist.min.js:8 Uncaught TypeError: Cannot read property 'querySelectorAll' of null
    at Object.c.createSvg (chartist.min.js:8)
    at f.d [as createChart] (chartist.min.js:8)
    at f.h (chartist.min.js:8)
chartist.min.js:8 Uncaught TypeError: Cannot read property 'querySelectorAll' of null
    at Object.c.createSvg (chartist.min.js:8)
    at f.d [as createChart] (chartist.min.js:8)
    at f.h (chartist.min.js:8)
index.html:222 Uncaught ReferenceError: wijmo is not defined
    at onload (index.html:222)

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建筑：
var node = document.createElement("div");                // Create a <div> node
var textnode = document.createTextNode("Extra Floor");   // Create a text node
node.appendChild(textnode);                              // Append the text to <div>
document.getElementById("building").appendChild(node);     // Append <div> to the building with id="building"