<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.3/css/select2.min.css">
<script src="http://cdnjs.cloudflare.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
<link rel="stylesheet" href="jquery.sweet-modal.min.css">
<title>Document</title>
</head>
<body>
<div class="wrapper">
<select id="parent_select">
<option>----</option>
</select>
<select id="child_select"></select>
</div>
<script language="javascript" type="text/javascript">
var mList = {
Chocolates: [
'Bournville',
'Snickers',
'Twix',
'Ferrero Rocher',
'Dark Chocolate',
'Milk chocolate',
'White chocolate',
'Gianduja chocolate'
],
Vegetables: [
'Broccoli',
'Cabbage',
'Carrot',
'Cauliflower'
],
Icecreams: [
'Black Raspberry',
'Frozen pudding',
'Neapolitan',
'Strawberry',
'Vanilla',
'Chokecherry',
'Frozen yogurt',
'Booza',
'Frozen yogurt',
'Ice milk'
],
Mobiles: [
'Apple iPhone',
'Samsung Galaxy',
'Realme',
'Huawei',
'OnePlus',
'Asus ROG',
'Xiaomi',
'Vivo'
]
};
el_parent = document.getElementById("parent_select");
el_child = document.getElementById("child_select");
for (key in mList) {
el_parent.innerHTML = el_parent.innerHTML + '<option>' + key + '</option>';
}
el_parent.addEventListener('change', function populate_child(e) {
el_child.innerHTML = '';
itm = e.target.value;
if (itm in mList) {
for (i = 0; i < mList[itm].length; i++) {
el_child.innerHTML = el_child.innerHTML + '<option>' + mList[itm][i] + '</option>';
}
}
});
</script>
</body>
</html>
