笔记——document.createElement创建添加属性

动态添加div中，需要进行添加id，class，style等属性

做下记录

var div = document.createElement('div');
div.id = 'mask_div1';
div.className = 'mask';
div.appendChild(document.createTextNode("test"));
div.style.position = "absolute";
div.style.left =  '20px';
div.style.top =  '20px';
div.style.overflow = "hidden";
div.style.zIndex = "9999";
div.style.opacity = 0.3;