<html lang="en"><head><title>Javascript Open Selectbox Dropdown on Hover</title><script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script><script>function JSDropDown() { var x = document.getElementById("mydropdown").options.length; document.getElementById("mydropdown").size = x;}</script></head><body><h2>Javascript Open Selectbox Dropdown on Hover</h2><select id="mydropdown" onmouseover="JSDropDown()" onmouseout="this.size=1;"> <option>Select Your Option</option> <option>Single</option> <option>Married</option></select></body></html>