Is there any way to compare negative 0 ie. -0 which is returned from Math.sign(-0)?

Question

I'm using JavaScript Date() utility in my code to get the today's tasks by comparing two different dates.

otApp.TaskPanelUtils.getDaysDiff = function(task)
    {
        var current = new Date();
        var taskDueDate = new Date(task.unformattedDueDate())
        return Math.trunc((current.getTime()-taskDueDate.getTime())/otApp.TaskPanelUtils.oneDay);
    }

var daysDiff = otApp.TaskPanelUtils.getDaysDiff(taskItem);

if(daysDiff==0 && Math.sign(daysDiff)==0)
{
    tempItems.push(taskItem);
}

The above code is working even if I get "-0" negative 0 as result of getDaysDiff().

I want to fill tempItems only in case of positive "0".

Math.sign(-0) will return -0, then how come comparision with "-0" or -0 is not working?

Possible duplicate of [Differentiating +0 and -0](http://stackoverflow.com/questions/7223717/differentiating-0-and-0) — JJJ, Mar 21 '16 at 11:31
You really should choose one question. Either "is there a way" or "how come it is not working". — Oleg V. Volkov, Mar 21 '16 at 11:33
Possible duplicate of [Are +0 and -0 the same?](http://stackoverflow.com/questions/7223359/are-0-and-0-the-same) — whd, Mar 21 '16 at 11:36
Are you even getting -0 returned value from `getDaysDiff` method? — gurvinder372, Mar 21 '16 at 11:39
Hi @gurvinder372, Yes I'm getting -0 from getDaysDiff, as I'm truncating -0.9898 all those to -0. — Raju Putchala, Mar 21 '16 at 11:44
So, you want to push those items for whom result is positive? does the actual daydiff matter to you? — gurvinder372, Mar 21 '16 at 11:46
Yes, I want to put only positives in a specific situation.. In this scenario I want to put items for which daysDiff() is positive zero.. — Raju Putchala, Mar 21 '16 at 11:49

gurvinder372 · Accepted Answer · 2016-03-21T11:53:11.337

1

The above code is working even if I get "-0" negative 0 as result of getDaysDiff().

Because 0 and -0 evaluate to 0.

Math.sign(-0) == Math.sign(0) //outputs true

0 == -0; //outputs true

0 === -0 //outputs true

String(-0) //outputs "0"

Edit:

I would suggest to simplify/modify the function so that it returns a boolean

otApp.TaskPanelUtils.getDaysDiff = function(task)
{
    var current = new Date();
    var taskDueDate = new Date(task.unformattedDueDate())
    return ((current.getTime()-taskDueDate.getTime())/otApp.TaskPanelUtils.oneDay) > 0;
}

And use it as

if(otApp.TaskPanelUtils.getDaysDiff(taskItem))
{
    tempItems.push(taskItem);
}

edited Mar 21 '16 at 11:53

answered Mar 21 '16 at 11:29

gurvinder372

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Hi @gurvinder372, Math.sign(-0) will return -0 and Math.sign(0) will return 0, according to the docs https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/sign, how to consume Math.sign(-0) for comparing negarive zero. – Raju Putchala Mar 21 '16 at 11:46
@RajuPutchala `Object.is(0,-0)` should give `false`. However, I don;t think you need to do that. Just return true/false from getDiff method if value < 0. – gurvinder372 Mar 21 '16 at 11:48
Hi @gurvinder372, the above suggested code is working fine..thanks you – Raju Putchala Mar 21 '16 at 12:20
@RajuPutchala Glad to help, Please accept and upvote the best answer that has helped you http://meta.stackexchange.com/questions/5234/how-does-accepting-an-answer-work – gurvinder372 Mar 21 '16 at 12:25

Is there any way to compare negative 0 ie. -0 which is returned from Math.sign(-0)?

1 Answers1