時間字串比較

var startTime='2018-09-03'; 
var endTime='2018-09-06'; 
var startDate = new Date(Date.parse(startTime.replace(/-/g,"/")));
var endDate = new Date(Date.parse(endTime.replace(/-/g,"/")));
if (startDate > endDate) {
     alert(startDate > endDate);
}

 時間字串加減一天

//加一天
function addDate(time) {
    //加一天
    var timestamp = Date.parse(new Date(time));
    timestamp = timestamp /1000;
    timestamp += 86400;//加一天
    var newTime =new Date(timestamp * 1000).format('yyyy-MM-dd');
    return newTime;
}

//減一天
function delDate(time) {
    var timestamp = Date.parse(new Date(time));
    timestamp = timestamp /1000;
    timestamp -= 86400;//加一天
    var newTime =new Date(timestamp * 1000).format('yyyy-MM-dd');
    return newTime;
}

//日期格式
Date.prototype.format = function(format) {
    var date = {
        "M+": this.getMonth() + 1,
        "d+": this.getDate(),
        "h+": this.getHours(),
        "m+": this.getMinutes(),
        "s+": this.getSeconds(),
        "q+": Math.floor((this.getMonth() + 3) / 3),
        "S+": this.getMilliseconds()
    };
    if (/(y+)/i.test(format)) {
        format = format.replace(RegExp.$1, (this.getFullYear() + '').substr(4 - RegExp.$1.length));
    }
    for (var k in date) {
        if (new RegExp("(" + k + ")").test(format)) {
            format = format.replace(RegExp.$1, RegExp.$1.length == 1
                ? date[k] : ("00" + date[k]).substr(("" + date[k]).length));
        }
    }
    return format;
}