bootstrap daterangepicker汉化以及扩展功能

/* 扩展该组件：增加一个select */  var _this = this;  var selectItem = '<select id="dateranepicker_select" class="form-control width150 inline-block">';  selectItem += '<option>今日</option>';  selectItem += '<option>昨日</option>';  selectItem += '<option selected="selected">最近7日</option>';  selectItem += '<option>最近15日</option>';  selectItem += '<option>最近30日</option>';  selectItem += '<option>本月</option>';  selectItem += '<option>上月</option>';  selectItem += '</select>';  this.element.parent().append(selectItem);  $(document).on('change','#dateranepicker_select',function(){   function auto0(num){    return num>10?num:'0'+num;   }   var val = $(this).val();   var c_start_date = new Date();   var c_end_date = new Date();   if(val=='今日'){   }   else if(val=='昨日'){    c_start_date.setDate(c_start_date.getDate()-1);    c_end_date.setDate(c_end_date.getDate()-1);   }   else if(val=='最近7日'){    c_start_date.setDate(c_start_date.getDate()-7);    c_end_date.setDate(c_end_date.getDate()-1);   }   else if(val=='最近15日'){    c_start_date.setDate(c_start_date.getDate()-15);    c_end_date.setDate(c_end_date.getDate()-1);   }   else if(val=='最近30日'){    c_start_date.setDate(c_start_date.getDate()-30);    c_end_date.setDate(c_end_date.getDate()-1);   }   else if(val=='本月'){    var cyear = c_start_date.getFullYear();    var cmonth = c_start_date.getMonth();    c_start_date = new Date(cyear,cmonth,1);    c_end_date =new Date(cyear+'-'+ (cmonth+1) +'-'+new Date(cyear,cmonth+1,0).getDate());   }   else if(val=='上月'){    var cyear = c_start_date.getFullYear();    var cmonth = c_start_date.getMonth()-1;    c_start_date = new Date(cyear,cmonth,1);    c_end_date =new Date(cyear+'-'+ (cmonth+1) +'-'+new Date(cyear,cmonth+1,0).getDate());   }   _this.setStartDate(c_start_date);   _this.setEndDate(c_end_date);   timespanStr =auto0(c_start_date.getMonth()+1)+'/'+ auto0(c_start_date.getDate()) + '/'+c_start_date.getFullYear()+'-'+ auto0(c_end_date.getMonth()+1) + '/' +auto0(c_end_date.getDate()) + '/' +c_end_date.getFullYear();   _this.element.val(timespanStr);   _this.hide();   _this.element.trigger('apply.daterangepicker', _this);   /* 扩展该组件 end */  });