节点插入

if(typeof HTMLElement !==‘undefined‘ && !HTMLElement.prototype.insertAdjacentHTML){
            var insertAdjacentElement = function(node,position,el){
                switch (position.toLowerCase()){
                    case ‘beforebegin‘:
                        node.parentNode.insertBefore(el,node);
                        break;
                    case ‘afterbegin‘:
                        node.insertBefore(el,node.firstChild);
                        break;
                    case ‘beforeend‘:
                        node.appendChild(el);
                        break;
                    case ‘afterend‘:
                        if(node.nextSibling){
                            node.parentNode.insertBefore(el,node.nextSibling);
                        }else{
                            node.parentNode.appendChild(el);
                        }
                        break;
                }
            };
            HTMLElement.prototype.insertAdjacentHTML = function(position,html){
                var range = document.createRange(),frag,
                        parent;
                range.setStart(document.body);
                frag = range.createContextualFragment(html);
                if(this.nodeType == 3 || this.nodeType == 8){
                    parent = this.parentNode;
                    insertAdjacentElement(parent,position,frag);
                }else{
                    insertAdjacentElement(this,position,frag);
                }
            }
        }