CodingForums.com - Resolved Trying to get the days between dates.

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- - Resolved Trying to get the days between dates. (http://www.codingforums.com/showthread.php?t=288368)

JonBMN

02-27-2013 02:51 AM

Trying to get the days between dates.

no regexp please. I feel my logic is sound on this but I'm definitely doing something wrong. Is it a logic error on my part or am I not passing Date.parse with the right value. I'm not sure please help! thank you for your replies! :)

Code:

//days between function only yyyy-mm-dd will work.

function daysBetween(firstd, secondd, string) {

        var date1 = firstd,

                date1 = Date.parse(date1),

                date2 = secondd,

                date2 = Date.parse(date2),

                str = string

                ;

        if (str === "days") {

                var day = 24 * 60 * 60 * 1000; //hours times minutes times seconds times milliseconds

                date1ms = date1.getTime();        //we convert both dates to milliseconds.

                date2ms = date2.getTime();

                var thedifference = Math.abs(date1ms - date2ms);

                return Math.round(thedifference / day);

        }

        else if (str === "hours") {

                var hour = 60 * 60 * 1000;

                date1ms = date1.getTime();

                date2ms = date2.getTime();

                var thedifference = Math.abs(date1ms - date2ms);

                return Math.round(thedifference / hour);

        }

}

Old Pedant

02-27-2013 02:55 AM

Date.parse() *ALREADY* is giving you the milliseconds since 1/1/1970.

It is handing you simply a *NUMBER*.

It is *NOT* giving you a Date object, so trying to do date.getTime() is giving you an error.

Time to learn to DEBUG DEBUG DEBUG!

Any good debugger (I prefer Chrome's, for integration and ease of use) would have shown you what was in date1 and date2.

JonBMN

02-27-2013 02:58 AM

Ah! the little things haha; I shall go and do that. I use firebug by the way if theres really any difference between chromes. is there?

Old Pedant

02-27-2013 03:00 AM

Why do you persist in copying the function arguments to other variables?

Why not simply:

Code:

function daysBetween(firstd, secondd, str) 

{

    var date1 = Date.parse(firstd),

        date2 = Date.parse(secondd);

    ...

And, actually, there's nothing wrong with doing

Code:

function daysBetween(date1, date2, str) 

{

    date1 = Date.parse(date1);

    date2 = Date.parse(date2);

    ...

And may I point out that you repeated this code:

Code:

                date1ms = date1.getTime();        //we convert both dates to milliseconds.

                date2ms = date2.getTime();

                var thedifference = Math.abs(date1ms - date2ms);

for no apparent reason?

Of course, now you know that you could have done simply

Code:

var thedifference = Math.abs(date1 - date2);

Old Pedant

02-27-2013 03:02 AM

Quote:

Originally Posted by JonBMN (Post 1316258)

Ah! the little things haha; I shall go and do that. I use firebug by the way if theres really any difference between chromes. is there?

Try them both. Use the one you like better.

Chrome does a better job of presenting variables, including scope variables, in my opinion. But it's not like either is any slouch.

JonBMN

02-27-2013 03:09 AM

You are right about all of those; except to me its a little clearer at this stage because if I wanted to I could change those variable names without having to change the arguments, but I am a beginner.

Pertaining to all your other snippets I actually feel very good because I figured to do those after your first reply which was a great push in the right direction.

I'll definitely have to try the chrome one for future projects and and compare on how much I like them, but thanks for the suggestion!

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