jsは今日の日付かどうかを判断します.

//        
judgeTime(data){
    var date = data.toString();
    var year = date.substring(0, 4);
    var month = date.substring(4, 6);
    var day = date.substring(6, 8);
    var d1 = new Date(year + '/' + month + '/' + day);
    var dd = new Date();
    var y = dd.getFullYear();
    var m = dd.getMonth() + 1;
    var d = dd.getDate();
    var d2 = new Date(y + '/' + m + '/' + d);
    var iday = parseInt(d2 - d1) / 1000 / 60 / 60 / 24;
    return iday;
  },

var start_time="2018-07-31T14:00"   //         ，     replace          
// 

if(judgeTime(start_time.replace(/-|T|:/g, ''))==0){
    console.log('     ')
}