有没有办法让JSON.stringify一个HTML DOM对象？ [JavaScript的]

我试图加载一个外部html文件并将其中的内容加以串化，但似乎无法这样做，而不会产生不希望的结果。有没有办法做到这一点？

I am trying to load in a external html file and stringify the contents within the body but can't seem to do so without it producing undesired results. Is there even a way to do this?

var xhr = new XMLHttpRequest();

function loadFile(){
    xhr.open("GET", 'index.html');
    xhr.responseType = "document";
    xhr.send();
}

xhr.onload = function(data) {
    myData = data;
    myString = JSON.stringify(myData.srcElement.responseXML.body.children);
        console.log(myString)
       //logs: {"0":{},"length":1}

    }

loadFile();

但我需要加载的是实际的div内容，例如：

But what I need it to load is the actual div contents, ex:

//log: '<div id ='mydiv'>...</div>

我做错了什么？