In this Javascript video lesson you will 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 subcatories from a user.
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
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>
Javascript Form Select Change Tutorial Dynamic List Option Elements