把以下文件复制到一个文件内，命名为 timeObj.js
然后直接引用即可。

let timeObj = {};
/**
 * 生成当前日期时间
 * @returns {string}
 */
timeObj.createDateTime = function(){
    let date = new Date();
    return date.getFullYear() + '-' + (date.getMonth() + 1) + '-' + date.getDate() + ' ' + date.getHours() + ':' + date.getMinutes() + ':' + date.getSeconds();
};
/**
 * 生成前天日期
 * @returns {string}
 */
timeObj.createBeforeYesterday = function(){
    let today_date  = new Date();
    let hour = today_date.getHours();
    if(hour >= 0 && hour <= 5 ){
      today_date.setTime(today_date.getTime() - 24 * (2+1) * 60 * 60 * 1000);
    }else{
      today_date.setTime(today_date.getTime() - 24 * 2 * 60 * 60 * 1000);
    }
    let month = today_date.getMonth() + 1;
    if(month < 10){
        month = '0' + month;
    }
    let date = today_date.getDate();
    if(date < 10){
        date = '0' + date;
    }
    return today_date.getFullYear() + '-' + month + '-' + date;
};
/**
 * 生成昨天日期
 * @returns {string}
 */
timeObj.createYesterday = function(){
    let today_date  = new Date();
    
    let hour = today_date.getHours();
    if(hour >= 0 && hour <= 5 ){
      today_date.setTime(today_date.getTime() - 24 * (1 + 1) * 60 * 60 * 1000);
    }else{
      today_date.setTime(today_date.getTime() - 24 * 1 * 60 * 60 * 1000);
    }
    
    let month = today_date.getMonth() + 1;
    if(month < 10){
        month = '0' + month;
    }
    let date = today_date.getDate();
    if(date < 10){
        date = '0' + date;
    }
    return today_date.getFullYear() + '-' + month + '-' + date;
};
/**
 * 生成七天前日期
 * @returns {string}
 */
timeObj.createSevendaysago = function(){
    let today_date  = new Date();
    
    let hour = today_date.getHours();
    if(hour >= 0 && hour <= 5 ){
      today_date.setTime(today_date.getTime() - 24 * (7 + 1) * 60 * 60 * 1000);
    }else{
      today_date.setTime(today_date.getTime() - 24 * 7 * 60 * 60 * 1000);
    }
    let month = today_date.getMonth() + 1;
    if(month < 10){
        month = '0' + month;
    }
    let date = today_date.getDate();
    if(date < 10){
        date = '0' + date;
    }
    return today_date.getFullYear() + '-' + month + '-' + date;
};

/**
 * 生成三十天前日期
 * @returns {string}
 */
timeObj.createThirtydaysago = function(){
    let today_date  = new Date();
    
    let hour = today_date.getHours();
    if(hour >= 0 && hour <= 5 ){
      today_date.setTime(today_date.getTime() - 24 * (30 + 1) * 60 * 60 * 1000);
    }else{
      today_date.setTime(today_date.getTime() - 24 * 30 * 60 * 60 * 1000);
    }
  
    let month = today_date.getMonth() + 1;
    if(month < 10){
        month = '0' + month;
    }
    let date = today_date.getDate();
    if(date < 10){
        date = '0' + date;
    }
    return today_date.getFullYear() + '-' + month + '-' + date;
};
/**
 * 生成时间戳
 */
timeObj.getTime = function (){
    return new Date().getTime();
};