insertAdjacentElement这个函数没有定义如果那些js代码是你写的话，那你就好好检查一下这个函数是否定义。如果没有自己添加上就可以了。
TypeErrorTheelementspecified is not a valid element. Visualization of position names <!--beforebegin--><p><!--afterbegin--> foo <!--beforeend--></p><!--afterend--> Note:Thebeforebeginandafterendpositions work only if the node is in a tree and has an element parent. ...
SyntaxErrorThepositionspecified is not a recognised value. Visualization of position names <!--beforebegin--><p><!--afterbegin--> foo <!--beforeend--></p><!--afterend--> Note: beforebegin afterend Example beforeBtn.addEventListener('click',function(){para.insertAdjacentText('afterbegin',te...