Filtering in EJ2 JavaScript Dropdown List
4 Sep 202622 minutes to read
The DropDownList has built-in support to filter data items when allowFiltering is enabled. The filter
operation starts as soon as you start typing characters in the search box.
To display filtered items in the popup, filter the required data and return it to the DropDownList via the updateData method by using the filtering event.
The following sample illustrates how to query the data source and pass the data to the DropDownList through the updateData method in the filtering event.
//initiates the component
var ddlObject = new ej.dropdowns.DropDownList({
//bind the data manager instance to dataSource property
dataSource: new ej.data.DataManager({
url: 'https://services.odata.org/V4/Northwind/Northwind.svc/Customers',
adaptor: new ej.data.ODataV4Adaptor(),
crossDomain: true
}),
//bind the Query instance to query property
query: new ej.data.Query().select(['ContactName']),
//map the appropriate columns to fields property
fields: { value: 'ContactName'},
//set the placeholder to DropDownList input
placeholder: "Find a customer",
//set the filterType to searching operation
filterType: 'StartsWith',
//sort the resulted items
sortOrder: 'Ascending'
});
//render the component
ddlObject.appendTo('#ddlelement');<!DOCTYPE html><html lang="en"><head>
<title>Essential JS 2 DropDownList</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="description" content="Typescript UI Controls">
<meta name="author" content="Syncfusion">
<link href="styles.css" rel="stylesheet">
<link href="https://cdn.syncfusion.com/ej2/34.2.2/ej2-base/styles/material.css" rel="stylesheet">
<link href="https://cdn.syncfusion.com/ej2/34.2.2/ej2-inputs/styles/material.css" rel="stylesheet">
<link href="https://cdn.syncfusion.com/ej2/34.2.2/ej2-dropdowns/styles/material.css" rel="stylesheet">
<script src="https://cdn.syncfusion.com/ej2/34.2.2/dist/ej2.min.js" type="text/javascript"></script>
</head>
<body>
<div id="container" style="margin:0 auto; width:250px;">
<br>
<input type="text" id="ddlelement">
</div>
<script>
var ele = document.getElementById('container');
if(ele) {
ele.style.visibility = "visible";
}
</script>
<script src="index.js" type="text/javascript"></script>
</body></html>Limit the minimum filter character
When filtering the list items, you can set the limit for the character count at which the remote request is raised and filtered data is fetched for the DropDownList. This can be done by performing manual validation within the filter event handler.
In the following example, the remote request does not fetch the search data until the search key contains three characters.
//initiates the component
var searchData = new ej.data.DataManager({
url: 'https://services.odata.org/V4/Northwind/Northwind.svc/Customers',
adaptor: new ej.data.ODataV4Adaptor(),
crossDomain: true
});
var ddlObject = new ej.dropdowns.DropDownList({
dataSource: searchData,
query: new ej.data.Query().select(['ContactName', 'CustomerID']).take(7),
// map the appropriate column
fields: { text: 'ContactName', value: 'CustomerID' },
// set placeholder to DropDownList input element
placeholder:"Select customers",
//sort the resulted items
sortOrder: 'Ascending',
// set true to allowFiltering for enable filtering supports
allowFiltering: true,
//bind the filtering event handler
filtering: (e) => {
// load overall data when search key empty.
if(e.text == '') e.updateData(searchData);
else{
// restrict the remote request until search key contains 3 characters.
if (e.text.length < 3) { return; }
var query = new ej.data.Query().select(['ContactName', 'CustomerID']);
query = (e.text !== '') ? query.where('ContactName', 'startswith', e.text, true) : query;
e.updateData(searchData, query);
}
}
});
//render the component
ddlObject.appendTo('#ddlelement');<!DOCTYPE html><html lang="en"><head>
<title>Essential JS 2 DropDownList</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="description" content="Typescript UI Controls">
<meta name="author" content="Syncfusion">
<link href="styles.css" rel="stylesheet">
<link href="https://cdn.syncfusion.com/ej2/34.2.2/ej2-base/styles/material.css" rel="stylesheet">
<link href="https://cdn.syncfusion.com/ej2/34.2.2/ej2-inputs/styles/material.css" rel="stylesheet">
<link href="https://cdn.syncfusion.com/ej2/34.2.2/ej2-dropdowns/styles/material.css" rel="stylesheet">
<script src="https://cdn.syncfusion.com/ej2/34.2.2/dist/ej2.min.js" type="text/javascript"></script>
</head>
<body>
<div id="container" style="margin:0 auto; width:250px;">
<br>
<input type="text" id="ddlelement">
</div>
<script>
var ele = document.getElementById('container');
if(ele) {
ele.style.visibility = "visible";
}
</script>
<script src="index.js" type="text/javascript"></script>
</body></html>Change the filter type
While filtering, you can change the filter type to contains, startsWith, or endsWith for string-type data within the filter event handler.
The following example performs filtering using the endsWith type.
//initiates the component
var searchData = new ej.data.DataManager({
url: 'https://services.odata.org/V4/Northwind/Northwind.svc/Customers',
adaptor: new ej.data.ODataV4Adaptor(),
crossDomain: true
});
var ddlObject = new ej.dropdowns.DropDownList({
dataSource: searchData,
query: new ej.data.Query().select(['ContactName', 'CustomerID']).take(7),
// map the appropriate column
fields: { text: 'ContactName', value: 'CustomerID' },
// set placeholder to DropDownList input element
placeholder:"Select customers",
//sort the resulted items
sortOrder: 'Ascending',
// set true to allowFiltering for enable filtering supports
allowFiltering: true,
//bind the filtering event handler
filtering: (e) => {
// load overall data when search key empty.
if(e.text == '') e.updateData(searchData);
else{
var query = new ej.data.Query().select(['ContactName', 'CustomerID']);
query = (e.text !== '') ? query.where('ContactName', 'startswith', e.text, true) : query;
e.updateData(searchData, query);
}
}
});
//render the component
ddlObject.appendTo('#ddlelement');<!DOCTYPE html><html lang="en"><head>
<title>Essential JS 2 DropDownList</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="description" content="Typescript UI Controls">
<meta name="author" content="Syncfusion">
<link href="styles.css" rel="stylesheet">
<link href="https://cdn.syncfusion.com/ej2/34.2.2/ej2-base/styles/material.css" rel="stylesheet">
<link href="https://cdn.syncfusion.com/ej2/34.2.2/ej2-inputs/styles/material.css" rel="stylesheet">
<link href="https://cdn.syncfusion.com/ej2/34.2.2/ej2-dropdowns/styles/material.css" rel="stylesheet">
<script src="https://cdn.syncfusion.com/ej2/34.2.2/dist/ej2.min.js" type="text/javascript"></script>
</head>
<body>
<div id="container" style="margin:0 auto; width:250px;">
<br>
<input type="text" id="ddlelement">
</div>
<script>
var ele = document.getElementById('container');
if(ele) {
ele.style.visibility = "visible";
}
</script>
<script src="index.js" type="text/javascript"></script>
</body></html>Case-sensitive filtering
Data items can be filtered either with or without case sensitivity by setting the ignoreCase property of the DropDownList.
The following example shows how to perform case-sensitive filtering.
//initiates the component
var searchData = new ej.data.DataManager({
url: 'https://services.odata.org/V4/Northwind/Northwind.svc/Customers',
adaptor: new ej.data.ODataV4Adaptor(),
crossDomain: true
});
var ddlObject = new ej.dropdowns.DropDownList({
dataSource: searchData,
query: new ej.data.Query().select(['ContactName', 'CustomerID']).take(7),
// map the appropriate column
fields: { text: 'ContactName', value: 'CustomerID' },
// set placeholder to DropDownList input element
placeholder:"Select customers",
//sort the resulted items
sortOrder: 'Ascending',
// set true to allowFiltering for enable filtering supports
allowFiltering: true,
//bind the filtering event handler
filtering: (e) => {
// load overall data when search key empty.
if(e.text == '') e.updateData(searchData);
else{
var query = new ej.data.Query().select(['ContactName', 'CustomerID']);
query = (e.text !== '') ? query.where('ContactName', 'startswith', e.text, true) : query;
e.updateData(searchData, query);
}
}
});
//render the component
ddlObject.appendTo('#ddlelement');<!DOCTYPE html><html lang="en"><head>
<title>Essential JS 2 DropDownList</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="description" content="Typescript UI Controls">
<meta name="author" content="Syncfusion">
<link href="styles.css" rel="stylesheet">
<link href="https://cdn.syncfusion.com/ej2/34.2.2/ej2-base/styles/material.css" rel="stylesheet">
<link href="https://cdn.syncfusion.com/ej2/34.2.2/ej2-inputs/styles/material.css" rel="stylesheet">
<link href="https://cdn.syncfusion.com/ej2/34.2.2/ej2-dropdowns/styles/material.css" rel="stylesheet">
<script src="https://cdn.syncfusion.com/ej2/34.2.2/dist/ej2.min.js" type="text/javascript"></script>
</head>
<body>
<div id="container" style="margin:0 auto; width:250px;">
<br>
<input type="text" id="ddlelement">
</div>
<script>
var ele = document.getElementById('container');
if(ele) {
ele.style.visibility = "visible";
}
</script>
<script src="index.js" type="text/javascript"></script>
</body></html>Diacritics Filtering
The DropDownList supports diacritics filtering, which ignores diacritics and makes it easier to filter results in lists that contain international characters when the ignoreAccent property is enabled.
In the following sample, the data with diacritics is bound as the dataSource for the DropDownList.
// create local data
var data = [
'Aeróbics',
'Aeróbics en Agua',
'Aerografía',
'Aeromodelaje',
'Águilas',
'Ajedrez',
'Ala Delta',
'Álbumes de Música',
'Alusivos',
'Análisis de Escritura a Mano'];
// initialize DropDownList component
var ddlObj = new ej.dropdowns.DropDownList({
//set the local data to dataSource property
dataSource: data,
// set the placeholder to DropDownList input element
placeholder: 'Select a value',
// enabled the ignoreAccent property for ignore the diacritics
ignoreAccent: true,
// set true for enable the filtering support.
allowFiltering: true,
filterBarPlaceholder: 'e.g: aero'
});
ddlObj.appendTo('#ddlelement');<!DOCTYPE html><html lang="en"><head>
<title>Essential JS 2 DropDownList</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="description" content="Typescript UI Controls">
<meta name="author" content="Syncfusion">
<link href="styles.css" rel="stylesheet">
<link href="https://cdn.syncfusion.com/ej2/34.2.2/ej2-base/styles/material.css" rel="stylesheet">
<link href="https://cdn.syncfusion.com/ej2/34.2.2/ej2-inputs/styles/material.css" rel="stylesheet">
<link href="https://cdn.syncfusion.com/ej2/34.2.2/ej2-dropdowns/styles/material.css" rel="stylesheet">
<script src="https://cdn.syncfusion.com/ej2/34.2.2/dist/ej2.min.js" type="text/javascript"></script>
</head>
<body>
<div id="container" style="margin:0 auto; width:250px;">
<br>
<input type="text" id="ddlelement">
</div>
<script>
var ele = document.getElementById('container');
if(ele) {
ele.style.visibility = "visible";
}
</script>
<script src="index.js" type="text/javascript"></script>
</body></html>Debounce delay
You can use the debounceDelay property for filtering, enabling you to set a delay in milliseconds. This functionality helps reduce the frequency of filtering as you type, enhancing performance and responsiveness for a smoother user experience. By default, the debounceDelay is set to 300 ms. If you wish to disable this feature entirely, you can set it to 0 ms.
let sportsData = [
{ Id: 'Game1', Game: 'Badminton' },
{ Id: 'Game2', Game: 'Basketball' },
{ Id: 'Game3', Game: 'Cricket' },
{ Id: 'Game4', Game: 'Football' },
{ Id: 'Game5', Game: 'Golf' },
{ Id: 'Game6', Game: 'Hockey' },
{ Id: 'Game7', Game: 'Rugby' },
{ Id: 'Game8', Game: 'Snooker' }
];
// initialize DropDownList component
var listObj = new ej.dropdowns.DropDownList({
//set the data to dataSource property
dataSource: sportsData,
// maps the appropriate column to fields property
fields: { value: 'Game' },
//set the debounceDelay
debounceDelay :'300',
// set placeholder to DropDownList input element
placeholder: "Find a game"});
listObj.appendTo('#ddlelement');<!DOCTYPE html><html lang="en"><head>
<title>Essential JS 2 DropDownList</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="description" content="Typescript UI Controls">
<meta name="author" content="Syncfusion">
<link href="styles.css" rel="stylesheet">
<link href="https://cdn.syncfusion.com/ej2/34.2.2/ej2-base/styles/material.css" rel="stylesheet">
<link href="https://cdn.syncfusion.com/ej2/34.2.2/ej2-inputs/styles/material.css" rel="stylesheet">
<link href="https://cdn.syncfusion.com/ej2/34.2.2/ej2-dropdowns/styles/material.css" rel="stylesheet">
<script src="https://cdn.syncfusion.com/ej2/34.2.2/dist/ej2.min.js" type="text/javascript"></script>
</head>
<body>
<div id="container" style="margin:0 auto; width:250px;">
<br>
<input type="text" id="ddlelement">
</div>
<script>
var ele = document.getElementById('container');
if(ele) {
ele.style.visibility = "visible";
}
</script>
<script src="index.js" type="text/javascript"></script>
</body></html>