编辑代码

const rootElement = document.documentElement;

let res = []
function myGetElementById(root, str){
    const firstTier = rootElement.childNodes;
    for (let i = 0; i < firstTier.length; i++) {
         if(firstTier[i].id = str){
             res.push(firstTier[i])
         }
         myGetElementById(firstTier[i], str)
   }
}