SOURCE

const dom = document.getElementById('wrapper')
function dom2Json(rootDom) {
    const obj = {}
    obj.tag = rootDom.tagName;
    obj.className = rootDom.className;
    obj.children = handleChildren(rootDom)
    return obj;
}

// 递归处理
function handleChildren(rootDom) {
    const result = [];
    const childs = rootDom.children;
    if (!childs || childs.length === 0) {
        return result;
    }
    for (const child of childs) {
        const obj = {}
        obj.tag = child.tagName;
        obj.className = child.className;
        obj.children = handleChildren(child);
        result.push(obj);
    }
    return result;
}

const resp = dom2Json(dom)
console.log(resp)

<div id="wrapper" class="wrapper">
	<h1>snowpack</h1>
	<div>
		<span>主体</span>
    </div>
    <a>到底了</a>
</div>