var dov = document.getElementsByTagName('div')
var dcv = document.getElementById('myDiv')
console.log(dov[0])
console.log(dcv.className)
console.log(dcv.lang)
console.log(dcv.dir)
console.log(dcv.id)
dcv.id = "someOtherId"
console.log(dcv.id)
dcv.className = 'sadg'
console.log(dcv.className)
// dcv.getAttribute()
// dev.setAttribute()
// 要把新元素添加到文档树，可以使用 appendChild() 、 inser-
// tBefore() 或 replaceChild() 方法
// 创建DOM
var divs= document.createElement("div");
console.log(divs)
<div id="myDiv" class="bd" title="Body text" lang="en" dir="ltr"></div>