Work with a time span in Javascript

问题:

Using Date.js already, but can also use another library if necessary.

Not sure what is the best way to work with time deltas. Specifically, I want to display the time that has elapsed between now and a past date-time.

So I need to do something like this:

var elapsed_time = new Date() - pastDate;
pastDate.toString('days-hours-minutes-seconds');

Gotten it to mostly work using Date.js, but the problem is now I'm working with a Date object and not a timespan, so what should be an 23 hour time span is instead 23 hours after the Date's very first time:

var result = (new Date()) - past_date;
"result" is the number (probably milliseconds): 15452732

var result = (new Date() - past_date
"result" is a date from 1969: Wed Dec 31 1969 23:17:32

What I need is:

0 days 23 hours 17 minutes and 32 seconds

Any ideas?

回答1:

Sounds like you need moment.js

e.g.

moment().subtract('days', 6).calendar();

=> last Sunday at 8:23 PM

moment().startOf('hour').fromNow();

=> 26 minutes ago

Edit:

Pure JS date diff calculation:

var date1 = new Date("7/Nov/2012 20:30:00");
var date2 = new Date("20/Nov/2012 19:15:00");

var diff = date2.getTime() - date1.getTime();

var days = Math.floor(diff / (1000 * 60 * 60 * 24));
diff -=  days * (1000 * 60 * 60 * 24);

var hours = Math.floor(diff / (1000 * 60 * 60));
diff -= hours * (1000 * 60 * 60);

var mins = Math.floor(diff / (1000 * 60));
diff -= mins * (1000 * 60);

var seconds = Math.floor(diff / (1000));
diff -= seconds * (1000);

document.write(days + " days, " + hours + " hours, " + mins + " minutes, " + seconds + " seconds");

回答2:

If you're not too worried in accuracy after days, you can simply do the maths

function timeSince(when) { // this ignores months
    var obj = {};
    obj._milliseconds = (new Date()).valueOf() - when.valueOf();
    obj.milliseconds = obj._milliseconds % 1000;
    obj._seconds = (obj._milliseconds - obj.milliseconds) / 1000;
    obj.seconds = obj._seconds % 60;
    obj._minutes = (obj._seconds - obj.seconds) / 60;
    obj.minutes = obj._minutes % 60;
    obj._hours = (obj._minutes - obj.minutes) / 60;
    obj.hours = obj._hours % 24;
    obj._days = (obj._hours - obj.hours) / 24;
    obj.days = obj._days % 365;
    // finally
    obj.years = (obj._days - obj.days) / 365;
    return obj;
}

then timeSince(pastDate); and use the properties as you like.

Otherwise you can use .getUTC* to calculate it, but note it may be slightly slower to calculate

function timeSince(then) {
    var now = new Date(), obj = {};
    obj.milliseconds = now.getUTCMilliseconds() - then.getUTCMilliseconds();
    obj.seconds = now.getUTCSeconds() - then.getUTCSeconds();
    obj.minutes = now.getUTCMinutes() - then.getUTCMinutes();
    obj.hours = now.getUTCHours() - then.getUTCHours();
    obj.days = now.getUTCDate() - then.getUTCDate();
    obj.months = now.getUTCMonth() - then.getUTCMonth();
    obj.years = now.getUTCFullYear() - then.getUTCFullYear();
    // fix negatives
    if (obj.milliseconds < 0) --obj.seconds, obj.milliseconds = (obj.milliseconds + 1000) % 1000;
    if (obj.seconds < 0) --obj.minutes, obj.seconds = (obj.seconds + 60) % 60;
    if (obj.minutes < 0) --obj.hours, obj.minutes = (obj.minutes + 60) % 60;
    if (obj.hours < 0) --obj.days, obj.hours = (obj.hours + 24) % 24;
    if (obj.days < 0) { // months have different lengths
        --obj.months;
        now.setUTCMonth(now.getUTCMonth() + 1);
        now.setUTCDate(0);
        obj.days = (obj.days + now.getUTCDate()) % now.getUTCDate();
    }
    if (obj.months < 0)  --obj.years, obj.months = (obj.months + 12) % 12;
    return obj;
}

回答3:

You can use momentjs duration object

Example:

const diff = moment.duration(Date.now() - new Date(2010, 1, 1))
console.log(`${diff.years()} years ${diff.months()} months ${diff.days()} days ${diff.hours()} hours ${diff.minutes()} minutes and ${diff.seconds()} seconds`)

回答4:

Moment.js provides such functionality:

http://momentjs.com/

It's well documented and nice library.

It should go along the lines "Duration" and "Humanize of API http://momentjs.com/docs/#/displaying/from/

 var d1, d2; // Timepoints
 var differenceInPlainText = moment(a).from(moment(b), true); // Add true for suffixless text

回答5:

/**
 * 计算时间对象与当前时间的差距，并显示友好的文本 
 * English: Calculating the difference between the given time and the current time and then showing the results.
 */
function date2Text(date) {
    var milliseconds = new Date() - date;
    var timespan = new TimeSpan(milliseconds);
    if (milliseconds < 0) {
        return timespan.toString() + "之后";
    }else{
        return timespan.toString() + "前";
    }
}

/**
 * 用于计算时间间隔的对象
 * English: Using a function to calculate the time interval
 * @param milliseconds 毫秒数
 */
var TimeSpan = function (milliseconds) {
    milliseconds = Math.abs(milliseconds);
    var days = Math.floor(milliseconds / (1000 * 60 * 60 * 24));
    milliseconds -= days * (1000 * 60 * 60 * 24);

    var hours = Math.floor(milliseconds / (1000 * 60 * 60));
    milliseconds -= hours * (1000 * 60 * 60);

    var mins = Math.floor(milliseconds / (1000 * 60));
    milliseconds -= mins * (1000 * 60);

    var seconds = Math.floor(milliseconds / (1000));
    milliseconds -= seconds * (1000);
    return {
        getDays: function () {
            return days;
        },
        getHours: function () {
            return hours;
        },
        getMinuts: function () {
            return mins;
        },
        getSeconds: function () {
            return seconds;
        },
        toString: function () {
            var str = "";
            if (days > 0 || str.length > 0) {
                str += days + "天";
            }
            if (hours > 0 || str.length > 0) {
                str += hours + "小时";
            }
            if (mins > 0 || str.length > 0) {
                str += mins + "分钟";
            }
            if (days == 0 && (seconds > 0 || str.length > 0)) {
                str += seconds + "秒";
            }
            return str;
        }
    }
}