Display dropdown of last 3 months using javascript

Question

I am trying to display last 3 months of present month (including this total four months) using javascript in drop down

function writeMonthOptions() {
    var mon         


        

Answer 1

This function returns the n last months, including the current one:

function getLastMonths(n) {

    var months = new Array();

    var today = new Date();
    var year = today.getFullYear();
    var month = today.getMonth() + 1;

    var i = 0;
    do {
        months.push(year + (month > 9 ? "" : "0") + month);
        if(month == 1) {
            month = 12;
            year--;
        } else {
            month--;
        }
        i++;
    } while(i < n);

    return months;

}

Call:

document.write(getLastMonths(4));

Prints:

201211,201210,201209,201208

Demo

---

Then, adding those values within a dropdown box is quite easy:

function writeMonthOptions() {   

   var optionValues = getLastMonths(4);
   var dropDown = document.getElementById("monthList");

   for(var i=0; i<optionValues.length; i++) {
       var key = optionValues[i].slice(4,6);
       var value = optionValues[i];
       dropDown.options[i] = new Option(value, key);
    }

}

Just use:

writeMonthOptions();

Full example