code: function(editor, textArea, set){
      var that = this, iframe = editor.find('iframe');
  
      iframe.css({
        height: set.height
      }).on('load', function(){
        var conts = iframe.contents()
        ,iframeWin = iframe.prop('contentWindow')
        ,head = conts.find('head')
        ,style = $(['<style>'
          ,'*{margin: 0; padding: 0;}'
          ,'body{padding: 10px; line-height: 20px; overflow-x: hidden; word-wrap: break-word; font: 14px Helvetica Neue,Helvetica,PingFang SC,Microsoft YaHei,Tahoma,Arial,sans-serif; -webkit-box-sizing: border-box !important; -moz-box-sizing: border-box !important; box-sizing: border-box !important;}'
          ,'a{color:#01AAED; text-decoration:none;}a:hover{color:#c00}'
          ,'p{margin-bottom: 10px;}'
          ,'img{display: inline-block; border: none; vertical-align: middle;}'
          ,'pre{margin: 10px 0; padding: 10px; line-height: 20px; border: 1px solid #ddd; border-left-width: 6px; background-color: #F2F2F2; color: #333; font-family: Courier New; font-size: 12px;}'
        ,'</style>'].join(''))
        ,body = conts.find('body');
        
        head.append(style);
        body.attr('contenteditable', 'true').css({
          'min-height': set.height
        }).html(textArea.value||'');
  
        hotkey.apply(that, [iframeWin, iframe, textArea, set]); //快捷键处理
        toolActive.call(that, iframeWin, editor, set); //触发工具
  
      });
    }
docs: iframe初始化