CODEWITHSUNDEEP
javascript
Exception
Exception

Reputation: 8389

Checking day of the month and year giving me incorrect results

I am using the below code to check the day of the month but it is not working. Please help me on this 

  function daysInMonth(month, year) {
     var length =  new Date(year, month, 0).getDate();
     for(var i = 1; i < = length; i++)
     {
         console.log(new Date(year,month,i).getDay());
     }
  };

here is the fiddle. It returns me incorrect results..

Upvotes: 0

Views: 254

Answers (3)

oleq
oleq

Reputation: 15895

Here's the correct code:

function daysInMonth( month, year ) {
    var day;
    for( var i = 1 ; i <= new Date( year, month, 0 ).getDate() ; i++ ) {
        day = new Date( year, month-1, i );
        console.log( day, day.getDay() );
    }

};

daysInMonth( 12, 2012 );

The issue was due to the fact that months are indexed 0-11. Provided that first day of the week is Sunday:

daysInMonth( 12, 2012 );

Sat Dec 01 2012 00:00:00 GMT+0100 (CET) 6 //Sat
Sun Dec 02 2012 00:00:00 GMT+0100 (CET) 0 //Sun
Mon Dec 03 2012 00:00:00 GMT+0100 (CET) 1 //Mon
    ...
Mon Dec 31 2012 00:00:00 GMT+0100 (CET) 1 //Mon

Alternative, shorter code:

function daysInMonth( month, year ) {
    for( var i = new Date( year, month, 0 ).getDate(), d = new Date( year, month-1, 1 ).getDay() ; i-- ; )
        console.log( d++ % 7 );
};

Upvotes: 1

Paul S.
Paul S.

Reputation: 66404

The Date constructor takes param month as an integer between 0 and 11, so your fiddle, which uses daysInMonth(12,2012);​ is actually finding the days of the week in daysInMonth(0,2013);​, i.e. January 2013 not December 2012.

Here is some code that will make it work letting you use months as 1 to 12

function daysInMonth(month, year) {
    var i, length =  new Date(year, month, 0).getDate(); // get last day no. of previous month ( month 0 - 11 )
    month = month - 1; // set month int to what we want
    for (i = 1; i <= length; i++) {
        console.log(new Date(year,month,i).getDay()); // continue as before
    }
};

daysInMonth(12,2012);

Upvotes: 1

karaxuna
karaxuna

Reputation: 26940

This works:

console.log(new Date('12/15/2012').getDay());​

Paul S. was right, works like this:

console.log(new Date(2012, 11, 15));​

Appears that months start from 0, in your example:

daysInMonth(11,2012);​

Upvotes: 0

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