Javascript date parse plus string

Question

I have an application I'm building and I want to create a date object with a "plus string", similar to PHP's strtotime() method.

Basically I want to be able to say

var date = new Date("+30 seconds");

Is there a way to create a date this way? I want it to be able to accept basic time values:

• seconds
• minutes
• days
• years
• etc.

Answer 1

I went ahead and created a function myself since something else doesn't seem to exist.

function parseDate(date)
{
    if(date == "now" || date == "")
    {
        return new Date();
    }

    if(date.charAt("0") == "+")
    {
        date.replace("+", "");
        var cmp = date.split(" ");

        if(cmp[1].indexOf("seconds") > -1)
        {
            return new Date((new Date()).getTime() + (cmp[0] * 1000));
        }
        else if(cmp[1].indexOf("minutes") > -1)
        {
            return new Date((new Date()).getTime() + (cmp[0] * 60 * 1000));
        }
        else if(cmp[1].indexOf("hours") > -1)
        {
            return new Date((new Date()).getTime() + (cmp[0] * 60 * 60 * 1000));
        }
        else if(cmp[1].indexOf("days") > -1)
        {
            return new Date((new Date()).getTime() + (cmp[0] * 60 * 60 * 24 * 1000));
        }
        else if(cmp[1].indexOf("weeks") > -1)
        {
            return new Date((new Date()).getTime() + (cmp[0] * 60 * 60 * 24 * 7 * 1000));
        }
        else if(cmp[1].indexOf("months") > -1)
        {
            return new Date((new Date()).getTime() + (cmp[0] * 60 * 60 * 24 * 30 * 1000));
        }
        else if(cmp[1].indexOf("years") > -1)
        {
            return new Date((new Date()).getTime() + (cmp[0] * 60 * 60 * 24 * 365 * 1000));
        }
    }

    if(date.charAt("0") == "-")
    {
        var cmp = date.split(" ");

        if(cmp[1].indexOf("seconds") > -1)
        {
            return new Date((new Date()).getTime() + (cmp[0] * 1000));
        }
        else if(cmp[1].indexOf("minutes") > -1)
        {
            return new Date((new Date()).getTime() + (cmp[0] * 60 * 1000));
        }
        else if(cmp[1].indexOf("hours") > -1)
        {
            return new Date((new Date()).getTime() + (cmp[0] * 60 * 60 * 1000));
        }
        else if(cmp[1].indexOf("days") > -1)
        {
            return new Date((new Date()).getTime() + (cmp[0] * 60 * 60 * 24 * 1000));
        }
        else if(cmp[1].indexOf("weeks") > -1)
        {
            return new Date((new Date()).getTime() + (cmp[0] * 60 * 60 * 24 * 7 * 1000));
        }
        else if(cmp[1].indexOf("months") > -1)
        {
            return new Date((new Date()).getTime() + (cmp[0] * 60 * 60 * 24 * 30 * 1000));
        }
        else if(cmp[1].indexOf("years") > -1)
        {
            return new Date((new Date()).getTime() + (cmp[0] * 60 * 60 * 24 * 365 * 1000));
        }
    }

    return new Date(date);
}

This accepts the following inputs:

"now" | "": returns current date

Datestring: returns corresponding date (this already worked in new Date(dateString))

[+ | -][#] [timevar]: returns current time [+ | -] [#] of [timevar]
     e.g. "+30 seconds"

Answer 2

As far as I know even very popular libraries like moment.js don't implement this feature. Also this strtotime implementation for Javascript doesn't handle your input.

So I guess we'll have to write it ourselves. This could get you started:

var parsePlus = (function () {
    "use strict";

    var converter = {
        'second': 1000,
        'minute': 1000 * 60,
        'hour': 1000 * 60 * 60
    };

    return function (input) {
        var sign = (input[0] === "+" || input[0] !== "-") ? 1 : -1,
            current = new Date().getTime();

        var parts = input.match(/(\+|-)?(\d+)\s*(second|minute|hour)s?/i);
        return new Date(current + sign * parts[2] * converter[parts[3]]);
    }
})();

console.log(parsePlus("+30seconds"));
console.log(parsePlus("-1hour"));

Answer 3

the Date function accepts numerical values

new Date(2011, 0, 1, 2, 3, 4, 567) // 1 Jan 2011, 02:03:04.567 in local timezone

you could use a function that splits a string by whitespace and feeds it to the Date object constructor

function s2date(s){return new Date(s.split(' '))}

Answer 4

No. You can't do var date = new Date("+30 seconds"); But you can do something like:

var date = new Date( Date.now() + (30 * 1000) );

If you wanted to build that into a function, you'd have to split the string and determine how many milliseconds to add:

function AddDate(string, timestamp){
    var s = string.split(' '), increaseby, newtime;
    switch(s[1]){
       case 'seconds':
           increaseby = 1000; // milliseconds in one second
           break;
       case 'minutes':
           increaseby = 1000 * 60; // milliseconds in a minute
           break;
    }

    newtime = (+s[0]) * increaseby;
    return timestamp + newtime;
}

(Or something like that.)