我正在创建一个应用程序，可让您定义带有时间范围的事件。 我想在用户选择或更改开始日期时自动填写结束日期。 但是，我不太清楚如何获得两次之间的差异，然后如何使用该差异创建新的结束日期。
在JavaScript中，可以通过调用getTime()方法或仅在数字表达式中使用日期，将日期转换为自epoc以来的毫秒数。
因此，要获得差异，只需减去两个日期。
要基于差异创建新日期，只需在构造函数中传递毫秒数即可。
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| var oldBegin = ...
var oldEnd = ...
var newBegin = ...
var newEnd = new Date(newBegin + oldEnd - oldBegin); |
这应该工作
编辑：修复了@bdukes指出的错误
编辑：
对于行为的解释，oldBegin，oldEnd和newBegin是Date实例。调用运算符+和-将触发Javascript自动转换，并将自动调用这些对象的valueOf()原型方法。碰巧valueOf()方法在Date对象中实现为对getTime()的调用。
所以基本上：date.getTime() === date.valueOf() === (0 + date) === (+date)
JavaScript完美支持开箱即用的日期差
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| var msMinute = 60*1000,
msDay = 60*60*24*1000,
a = new Date(2012, 2, 12, 23, 59, 59),
b = new Date("2013 march 12");
console.log(Math.floor((b - a) / msDay) + ' full days between');
console.log(Math.floor(((b - a) % msDay) / msMinute) + ' full minutes between'); |
现在有一些陷阱。尝试这个：
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| console.log(a - 10);
console.log(a + 10); |
因此，如果您有添加数字和日期的风险，请将日期直接转换为number。
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| console.log(a.getTime() - 10);
console.log(a.getTime() + 10); |
我的第一个例子演示了Date对象的功能，但实际上似乎是定时炸弹
参见JsFiddle演示
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| var date1 = new Date();
var date2 = new Date("2025/07/30 21:59:00");
//Customise date2 for your required future time
showDiff();
function showDiff(date1, date2){
var diff = (date2 - date1)/1000;
diff = Math.abs(Math.floor(diff));
var days = Math.floor(diff/(24*60*60));
var leftSec = diff - days * 24*60*60;
var hrs = Math.floor(leftSec/(60*60));
var leftSec = leftSec - hrs * 60*60;
var min = Math.floor(leftSec/(60));
var leftSec = leftSec - min * 60;
document.getElementById("showTime").innerHTML ="You have" + days +" days" + hrs +" hours" + min +" minutes and" + leftSec +" seconds before death.";
setTimeout(showDiff,1000);
} |
为您的HTML代码：
如果您不关心时间部分，则可以使用.getDate()和.setDate()设置日期部分。
因此，要将结束日期设置为开始日期之后的2周，请执行以下操作：
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| function GetEndDate(startDate)
{
var endDate = new Date(startDate.getTime());
endDate.setDate(endDate.getDate()+14);
return endDate;
} |
要返回两个日期之间的时差(以天为单位)，请执行以下操作：
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| function GetDateDiff(startDate, endDate)
{
return endDate.getDate() - startDate.getDate();
} |
最后，让我们修改第一个函数，使其可以将2nd返回的值用作参数：
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| function GetEndDate(startDate, days)
{
var endDate = new Date(startDate.getTime());
endDate.setDate(endDate.getDate() + days);
return endDate;
} |
感谢@Vincent Robert，我最终使用了您的基本示例，尽管它实际上是newBegin + oldEnd - oldBegin。这是简化的最终解决方案：
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| // don't update end date if there's already an end date but not an old start date
if (!oldEnd || oldBegin) {
var selectedDateSpan = 1800000; // 30 minutes
if (oldEnd) {
selectedDateSpan = oldEnd - oldBegin;
}
newEnd = new Date(newBegin.getTime() + selectedDateSpan));
} |
根据您的需要，此函数将计算两天之间的差，并以十进制天为单位返回结果。
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| // This one returns a signed decimal. The sign indicates past or future.
this.getDateDiff = function(date1, date2) {
return (date1.getTime() - date2.getTime()) / (1000 * 60 * 60 * 24);
}
// This one always returns a positive decimal. (Suggested by Koen below)
this.getDateDiff = function(date1, date2) {
return Math.abs((date1.getTime() - date2.getTime()) / (1000 * 60 * 60 * 24));
} |
如果使用moment.js，则有一个更简单的解决方案，它将在一行代码中为您带来几天的差异。
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| moment(endDate).diff(moment(beginDate), 'days'); |
其他细节可以在moment.js页面中找到
干杯，
米格尔
替代修改扩展代码
http://jsfiddle.net/vvGPQ/48/
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| showDiff();
function showDiff(){
var date1 = new Date("2013/01/18 06:59:00");
var date2 = new Date();
//Customise date2 for your required future time
var diff = (date2 - date1)/1000;
var diff = Math.abs(Math.floor(diff));
var years = Math.floor(diff/(365*24*60*60));
var leftSec = diff - years * 365*24*60*60;
var month = Math.floor(leftSec/((365/12)*24*60*60));
var leftSec = leftSec - month * (365/12)*24*60*60;
var days = Math.floor(leftSec/(24*60*60));
var leftSec = leftSec - days * 24*60*60;
var hrs = Math.floor(leftSec/(60*60));
var leftSec = leftSec - hrs * 60*60;
var min = Math.floor(leftSec/(60));
var leftSec = leftSec - min * 60;
document.getElementById("showTime").innerHTML ="You have" + years +" years"+ month +" month" + days +" days" + hrs +" hours" + min +" minutes and" + leftSec +" seconds the life time has passed.";
setTimeout(showDiff,1000);
} |
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| function compare()
{
var end_actual_time = $('#date3').val();
start_actual_time = new Date();
end_actual_time = new Date(end_actual_time);
var diff = end_actual_time-start_actual_time;
var diffSeconds = diff/1000;
var HH = Math.floor(diffSeconds/3600);
var MM = Math.floor(diffSeconds%3600)/60;
var formatted = ((HH < 10)?("0" + HH):HH) +":" + ((MM < 10)?("0" + MM):MM)
getTime(diffSeconds);
}
function getTime(seconds) {
var days = Math.floor(leftover / 86400);
//how many seconds are left
leftover = leftover - (days * 86400);
//how many full hours fits in the amount of leftover seconds
var hours = Math.floor(leftover / 3600);
//how many seconds are left
leftover = leftover - (hours * 3600);
//how many minutes fits in the amount of leftover seconds
var minutes = leftover / 60;
//how many seconds are left
//leftover = leftover - (minutes * 60);
alert(days + ':' + hours + ':' + minutes);
} |
这就是我在系统上执行的操作。
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| var startTime=("08:00:00").split(":");
var endTime=("16:00:00").split(":");
var HoursInMinutes=((parseInt(endTime[0])*60)+parseInt(endTime[1]))-((parseInt(startTime[0])*60)+parseInt(startTime[1]));
console.log(HoursInMinutes/60); |
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| <html>
<head>
function dayDiff()
{
var start = document.getElementById("datepicker").value;
var end= document.getElementById("date_picker").value;
var oneDay = 24*60*60*1000;
var firstDate = new Date(start);
var secondDate = new Date(end);
var diffDays = Math.round(Math.abs((firstDate.getTime() - secondDate.getTime())/(oneDay)));
document.getElementById("leave").value =diffDays ;
}
</head>
<body>
<input type="text" name="datepicker"value=""/>
<input type="text" name="date_picker" onclick="function dayDiff()" value=""/>
<input type="text" name="leave" value=""/>
</body>
</html> |
当您输入学习的开始日期和结束日期(合格日期)并检查持续时间是否少于一年(如果是)时，此代码将填满学习年限
请记住，有三个输入元素，第一个txtFromQualifDate和第二个txtQualifDate以及第三个txtStudyYears
它将显示分数的年数结果
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| function getStudyYears()
{
if(document.getElementById('txtFromQualifDate').value != '' && document.getElementById('txtQualifDate').value != '')
{
var d1 = document.getElementById('txtFromQualifDate').value;
var d2 = document.getElementById('txtQualifDate').value;
var one_day=1000*60*60*24;
var x = d1.split("/");
var y = d2.split("/");
var date1=new Date(x[2],(x[1]-1),x[0]);
var date2=new Date(y[2],(y[1]-1),y[0])
var dDays = (date2.getTime()-date1.getTime())/one_day;
if(dDays < 365)
{
alert("the date between start study and graduate must not be less than a year !");
document.getElementById('txtQualifDate').value ="";
document.getElementById('txtStudyYears').value ="";
return ;
}
var dMonths = Math.ceil(dDays / 30);
var dYears = Math.floor(dMonths /12) +"." + dMonths % 12;
document.getElementById('txtStudyYears').value = dYears;
}
} |
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| function checkdate() {
var indate = new Date()
indate.setDate(dat)
indate.setMonth(mon - 1)
indate.setFullYear(year)
var one_day = 1000 * 60 * 60 * 24
var diff = Math.ceil((indate.getTime() - now.getTime()) / (one_day))
var str = diff +" days are remaining.."
document.getElementById('print').innerHTML = str.fontcolor('blue')
} |
下面的代码将返回从今天到期货日期的剩余天数。
依赖关系：jQuery和MomentJs。
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| var getDaysLeft = function (date) {
var today = new Date();
var daysLeftInMilliSec = Math.abs(new Date(moment(today).format('YYYY-MM-DD')) - new Date(date));
var daysLeft = daysLeftInMilliSec / (1000 * 60 * 60 * 24);
return daysLeft;
};
getDaysLeft('YYYY-MM-DD'); |
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| var getDaysLeft = function (date1, date2) {
var daysDiffInMilliSec = Math.abs(new Date(date1) - new Date(date2));
var daysLeft = daysDiffInMilliSec / (1000 * 60 * 60 * 24);
return daysLeft;
};
var date1='2018-05-18';
var date2='2018-05-25';
var dateDiff = getDaysLeft(date1, date2);
console.log(dateDiff); |
如果使用Date对象，然后对两个日期都使用getTime()函数，它将为您提供自1970年1月1日以来的数字值。然后，您可以获取这些数字之间的差。
如果那对您没有帮助，请查看完整的文档：http://www.w3schools.com/jsref/jsref_obj_date.asp
