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JavaScript | date.setMonth() function

The date.setMonth() is an inbuilt function in JavaScript which is used to set month into a date object which is created using the Date() constructor.

Syntax:

DateObj.setMonth(month_Value);

DateObj is a valid Date object created using Date() constructor in which we want to set the month.Value of month is from 0 to 11 because the total number of months in a year is 12 from January to December.Vaue 0 is used for January, 1 for Febuary and so on till 11 for December.

Parameter: Here parameter month_Value is the value of month which we want to set in the date created using the Date() constructor.

Return Values: It returns the new i.e updated month which is set by setMonth() function.



Below program illustrates the setMonth() function:

// Here a date has been assigned
// while creating Date object
var dateobj = new Date('October 13, 1996 05:35:32');
  
// new month of January is being set in above Date
// Object with the help of setMonth() function
dateobj.setMonth(0);
  
// new month from above Date Object is
// being extracted using getMonth()
var B = dateobj.getMonth();
  
// Printing new month
console.log(B);

Output:

> 0

Errors and Exceptions

  • Code #1: If in Date() constructor we do not give any month while creating the date object, still setMonth() function will be able to set new month in the created date object.
    // Here month has not been assigned
    // while creating Date object
    var dateobj = new Date('1996, 05:35:32');
      
    // new month of 2 is being set in above Date
    // Object with the help of setMonth() function
    dateobj.setMonth(2);
      
    // new month from above Date Object is
    // being extracted using getMonth()
    var B = dateobj.getMonth();
      
    // Printing new month
    console.log(B);

    Output:

    > 2
  • Code #2: If nothing as parameter is given in Date() constructor, still setMonth() function will be able to set month but year, date etc remains current ones.
    // Here nothing has been assigned
    // while creating Date object
    var dateobj = new Date();
      
    // new month of 11 is being set in above Date
    // Object with the help of setMonth() function
    dateobj.setMonth(11);
      
    // Month from above Date Object is
    // being extracted using getMonth()
    var B = dateobj.getMonth();
      
    // date from above Date Object is
    // being extracted using getDate()
    var C = dateobj.getDate();
      
    // year from above Date Object is
    // being extracted using getFullYear()
    var D = dateobj.getFullYear();
      
    // Printing new month
    console.log(B);
      
    // Printing current date
    console.log(C);
      
    // Printing current year
    console.log(D);

    Output:

    > 11
    > 1
    > 2018

    Here 11 is the new month of December, 1 is the current date and 2018 is the current year.

  • Code #3: If value of month 15 is given as the parameter of setMonth() function, It will set 3 as the month because month range is form 0 to 11 and hence (15%12 = 3).
    // Here date has been assigned
    // while creating Date object
    var dateobj = new Date('October 13, 1996 05:35:32');
      
    // new month of 15 is being set in above Date
    // Object with the help of setMonth() function
    dateobj.setMonth(15);
      
    // month from above Date Object is
    // being extracted using getMonth()
    var B = dateobj.getMonth();
      
    // year from above Date Object is
    // being extracted using getFullYear()
    var C = dateobj.getFullYear();
      
    // Printing new month
    console.log(B);
      
    // Printing new year
    console.log(C);

    Output:

    > 3
    > 1997

    Here 3 is the new month of April and year becomes 1997 from 1996 because month range is form 0 to 11 i.e, total 12 and we set new month as 3 which increase year by one to 1997 from 1996 and month becomes 3.



This article is attributed to GeeksforGeeks.org

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