Dynamic Year List Dropdown

Form dropdown fields with year selections related to the current year need to be updated at the start of every year. That is, unless you have the dropdown set up to automatically stay current, which is what this article is about.

An example of selections related to the current year are credit card information forms, where you may want the current year and the next 6 years available for selection. Another example is a form to select the year for a calendar download, in which case the next year and some years thereafter should be selectable.

The first of the following examples lists the current year and next year. The second lists five year numbers, beginning with next year. The third lists the 8 previous years.

The above dropdown selection examples are created with this JavaScript. Following the code are instructions.

<select>
<option value="">-- Select Year --</option>
<script type="text/javascript">
var StartYear = +0; // use +0 to start with the current year; -1 for last year; +1 for next year; +3 for three years from now; or so forth.
var HowManyYears = 2; // How many years to list in the selection.
var today = new Date();
var year = today.getFullYear();
for(var i=0; i<HowManyYears; i++)
{
   var y = (year+StartYear)+i;
   document.write('<option value="' + y + '">' + y + '</option>');
}
</script>
</select>

The first 2 lines and the last line of the above code represent your selection form field:

• (line 1) your select tag.
• (line 2) the optional first selection for instructions.
• (last line) the closing </select> tag.

Your select tag might have an id attribute and/or a name attribute. It might also have other attributes.

In between the code that represents your selection form field is the JavaScript that writes the options with the year numbers. The JavaScript has two places to edit:

1. Update the +0 value in the var StartYear = +0; line.

   To start the dropdown list with the current year, specify +0 as the value.

   To start the list with last year, specify -1 as the value or to start the list with next year, specify +1.

   The digit you use represents the number of years. The "+" or "−" represents the next or past, respectively. As an example, +3 starts the dropdown list with the year number for 3 years in the future.

2. Update the 2 value in the var HowManyYears = 2; line.

   The number that 2 is replaced with tells the JavaScript how many year numbers to populate the dropdown with. (Year numbers will be sequential, ascending.)

The JavaScript automatically lists the year numbers in the dropdown in relation to the current year. It gives you a year list.

(This content first appeared in Possibilities newsletter.)

Will Bontrager