How to fix '.setFullYear is not a function'

Question

I receive an error Uncaught TypeError: thisDay.setFullYear is not a function while attempting to modify the values.

I've attempted debugging in various stages of the code and have confirmed that I am able to access the thisDay variable from within my moveDate function, it just does not allow me to use any date functions on it.

My code I have been fighting with is located at https://jsfiddle.net/ramseys1990/g9cp42bj/3/

The snippet of the main problem is:

function moveDate(selection) {

    switch(selection) {
        case "prevYear":
            thisDay.setFullYear((thisDay.getFullYear() - 1).toInteger);
            putCalendar(thisDay.getMonth(), thisDay.getFullYear() - 1);
            break;
        case "prevMonth":
            thisDay.setMonth(thisDay.getMonth() - 1);
            //putCalendar(thisDay.getMonth() - 1, thisDay.getFullYear());
            break;
        case "nextMonth":
            thisDay.setMonth(thisDay.getMonth() + 1);
            //putCalendar(thisDay.getMonth() + 1, thisDay.getFullYear());
            break;
        case "nextYear":
            thisDay.setFullYear(thisDay.getFullYear() + 1);
            //putCalendar(thisDay.getMonth(), thisDay.getFullYear() + 1);
            break;
        case "today":
            thisDay = new Date();
            //putCalendar(thisDay.getMonth(), thisDay.getFullYear());
            break;
    }
    putCalendar(thisDay.getMonth(), thisDay.getFullYear());
    return;
}

My putCalendar function is:

function putCalendar(month, year) {


    // Set the date displayed in the calendar 

    thisDay.setMonth = month;
    thisDay.setFullYear = year;
    // Determine the current month
    //var thisMonth = thisDay.getMonth();
    // Determine the current year
    //var thisYear = thisDay.getFullYear();

    // write the calendar to the element with the id 'calendar'
    document.getElementById("demo").innerHTML = createCalendar(thisDay);
}

And the top of my code file is currently:

"use strict";
var thisDay = new Date();
putCalendar(thisDay.getMonth(), thisDay.getFullYear());

I expect it to pass the modified date to my putCalendar function to recreate the calendar for a different year or month.

Answer 1

The problem is that here

putCalendar(thisDay.getMonth(), thisDay.getFullYear());

you call getFullYear and its return value gets passed to putCalendar , which is not a function .

Then year , and .setFullYear will get this value, and when you try to call it, it will fail.