elem.innerHTML =“<body></body>”无效。为什么?

elem.innerHTML = "<body></body>" isn't working. Why?

let t=document.createElement('template');

t.innerHTML = "<body></body>"

var E = t.children; // HTMLCollection { length: 0 }

t.innerHTML = "<div></div>"; 
var E = t.children; // HTMLCollection { 0: div, length: 1 }

正在解析 div 而不是正文,为什么正文标签没有被解析?

我在 windows 10

上使用 Firefox 99.0.1

Template elements 不允许包含正文元素。

parsing rules遇到

时说

A start tag whose tag name is "body" … if there is a template element on the stack of open elements, then ignore the token.