I created an HTML5 Form with many <select> tags and I wanted to obtain some of the values or options in my JavaScript code.

Question

I want to use the options the user created and use them in my JavaScript code. For example one select tag has many years in it and if the user selects a year below 2018. Then it alerts Welcome. How can I do it.
My codes are below: Help me solve and see if there's a mistake.
HTML CODE (Some are ignored)
<select name="dropdown">
<option class="miyear" value="select">2015</option>
<option class="miyear" value="select">2016</option>
<option class="miyear" value="select">2017</option>
<option class="miyear" value="select">2018</option>
<option class="miyear" value="select">2019</option>
</select>

JS CODE:
var yearofjoin=document.getElementsByClassName ("miyear");
var currentyear=getFullYear ();
var difference;
difference=currentyear-yearofjoin.value;
alert ("Welcome"+difference);

Answer 1

put class at select instead of option

and getElementsByClassName returns a HTMLCollection, so use [0]