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Form Select Change Dynamic List Option Elements Tutorial

Published : November 17, 2014   •   Last Edited : November 24, 2025   •   Author : Adam Khoury

Learn how to program dynamic select form list elements. To demonstrate the logic we will show how to change options of a select list based on the selection the user makes from the first list. A web application developer will definitely need to know how to do this when they get into form programming that involves data intake of categories and subcategories from a user.

<!DOCTYPE html>
<html>
<head>
<script>
function populate(s1,s2){
	var s1 = document.getElementById(s1);
	var s2 = document.getElementById(s2);
	s2.innerHTML = "";
	if(s1.value == "Chevy"){
		var optionArray = ["|","camaro|Camaro","corvette|Corvette","impala|Impala"];
	} else if(s1.value == "Dodge"){
		var optionArray = ["|","avenger|Avenger","challenger|Challenger","charger|Charger"];
	} else if(s1.value == "Ford"){
		var optionArray = ["|","mustang|Mustang","shelby|Shelby"];
	}
	for(var option in optionArray){
		var pair = optionArray[option].split("|");
		var newOption = document.createElement("option");
		newOption.value = pair[0];
		newOption.innerHTML = pair[1];
		s2.options.add(newOption);
	}
}
</script>
</head>
<body>
<h2>Choose Your Car</h2>
<hr />
Choose Car Make:
<select id="slct1" name="slct1" onchange="populate(this.id,'slct2')">
  <option value=""></option>
  <option value="Chevy">Chevy</option>
  <option value="Dodge">Dodge</option>
  <option value="Ford">Ford</option>
</select>
<hr />
Choose Car Model:
<select id="slct2" name="slct2"></select>
<hr />
</body>
</html>
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