10 Kendo UI Interview Questions and Answers
Prepare for your next technical interview with this guide on Kendo UI, featuring common questions and answers to help you demonstrate your expertise.
Kendo UI is a comprehensive JavaScript framework designed to help developers build modern, high-performance web applications. It offers a rich set of UI components, including grids, charts, and schedulers, which are essential for creating interactive and responsive user interfaces. With its seamless integration with popular frameworks like Angular, React, and Vue, Kendo UI has become a go-to choice for developers aiming to enhance their web applications’ functionality and user experience.
This article provides a curated selection of interview questions focused on Kendo UI, aimed at helping you demonstrate your proficiency and understanding of this powerful framework. By familiarizing yourself with these questions and their answers, you can confidently showcase your expertise and stand out in your technical interviews.
Kendo UI Interview Questions and Answers
1. Write a code snippet to initialize a DatePicker widget and set its value to today’s date.
To initialize a DatePicker widget in Kendo UI and set its value to today’s date, use the following code snippet. This example uses JavaScript to create the DatePicker and set its value.
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="https://kendo.cdn.telerik.com/2023.3.1010/styles/kendo.default-v2.min.css" />
<script src="https://kendo.cdn.telerik.com/2023.3.1010/js/jquery.min.js"></script>
<script src="https://kendo.cdn.telerik.com/2023.3.1010/js/kendo.all.min.js"></script>
</head>
<body>
<input id="datepicker" />
<script>
$(document).ready(function() {
$("#datepicker").kendoDatePicker({
value: new Date()
});
});
</script>
</body>
</html>
2. Explain the different types of data binding available.
Kendo UI offers several types of data binding to synchronize data between the UI and the data model. The primary types are:
- One-Way Binding: Updates the UI when the data source changes. Useful for displaying data without user interaction.
- Two-Way Binding: Ensures changes in the UI are reflected in the data source and vice versa. Ideal for capturing user input.
- One-Time Binding: Initializes the UI with data from the source but does not update it when the source changes. Suitable for static data.
3. Provide an example of how to handle the ‘change’ event for a DropDownList widget.
The ‘change’ event in Kendo UI’s DropDownList widget triggers when the selected item changes. This event is useful for executing custom logic when a user selects a different item.
Here is an example of handling the ‘change’ event for a DropDownList widget:
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="https://kendo.cdn.telerik.com/2023.3.1010/styles/kendo.default-v2.min.css">
<script src="https://kendo.cdn.telerik.com/2023.3.1010/js/jquery.min.js"></script>
<script src="https://kendo.cdn.telerik.com/2023.3.1010/js/kendo.all.min.js"></script>
</head>
<body>
<select id="dropdownlist"></select>
<script>
$(document).ready(function() {
$("#dropdownlist").kendoDropDownList({
dataSource: ["Item1", "Item2", "Item3"],
change: function(e) {
var selectedValue = this.value();
console.log("Selected value: " + selectedValue);
}
});
});
</script>
</body>
</html>
In this example, the DropDownList is initialized with a data source containing three items. The ‘change’ event logs the selected value to the console.
4. Write a code snippet to create a Grid with three columns: Name, Age, and Email, and bind it to a local data source.
To create a Kendo UI Grid with three columns: Name, Age, and Email, and bind it to a local data source, use the following code snippet:
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="https://kendo.cdn.telerik.com/2023.3.1010/styles/kendo.default-v2.min.css">
<script src="https://kendo.cdn.telerik.com/2023.3.1010/js/jquery.min.js"></script>
<script src="https://kendo.cdn.telerik.com/2023.3.1010/js/kendo.all.min.js"></script>
</head>
<body>
<div id="grid"></div>
<script>
$(document).ready(function() {
var localData = [
{ Name: "John Doe", Age: 30, Email: "[email protected]" },
{ Name: "Jane Smith", Age: 25, Email: "[email protected]" },
{ Name: "Samuel Green", Age: 35, Email: "[email protected]" }
];
$("#grid").kendoGrid({
dataSource: {
data: localData,
schema: {
model: {
fields: {
Name: { type: "string" },
Age: { type: "number" },
Email: { type: "string" }
}
}
},
pageSize: 10
},
height: 400,
scrollable: true,
sortable: true,
pageable: true,
columns: [
{ field: "Name", title: "Name" },
{ field: "Age", title: "Age" },
{ field: "Email", title: "Email" }
]
});
});
</script>
</body>
</html>
5. How can you create a custom editor for a column in a Grid? Provide a code example.
In Kendo UI, a custom editor for a column in a Grid can be created by defining a custom editor function. This function replaces the default editor, allowing for more control over the editing experience. The custom editor function is specified in the column definition of the Grid.
Example:
$(document).ready(function() {
$("#grid").kendoGrid({
dataSource: {
data: [
{ id: 1, name: "John Doe", age: 30 },
{ id: 2, name: "Jane Smith", age: 25 }
],
schema: {
model: {
id: "id",
fields: {
id: { editable: false, nullable: true },
name: { type: "string" },
age: { type: "number" }
}
}
}
},
columns: [
{ field: "name", title: "Name" },
{ field: "age", title: "Age", editor: customEditor }
],
editable: true
});
function customEditor(container, options) {
$('<input name="' + options.field + '"/>')
.appendTo(container)
.kendoNumericTextBox({
min: 0,
max: 100
});
}
});
6. How do you ensure accessibility in components? Provide specific examples.
Ensuring accessibility in Kendo UI components involves adhering to the Web Content Accessibility Guidelines (WCAG) and using ARIA (Accessible Rich Internet Applications) attributes. Kendo UI provides several built-in features to help developers create accessible applications.
Keyboard Navigation: Kendo UI components support keyboard navigation, allowing users to interact with the application using only the keyboard.
ARIA Support: Kendo UI components come with ARIA attributes that provide additional context to screen readers. For example, the Kendo UI Grid includes ARIA roles and properties to describe the structure and state of the grid to assistive technologies.
High Contrast Themes: Kendo UI offers high contrast themes to ensure that the components are usable for users with visual impairments. These themes are designed to meet the contrast requirements specified by WCAG.
Focus Management: Proper focus management is essential for accessibility. Kendo UI components manage focus appropriately, ensuring that focus is moved to the correct element when interacting with the components.
Validation and Error Messages: Kendo UI forms and input components provide accessible validation and error messages. These messages are announced by screen readers, ensuring that users are aware of any issues with their input.
7. Explain how to implement internationalization (i18n) in an application.
Internationalization (i18n) is the process of designing and developing an application so that it can be easily adapted to various languages and regions without requiring engineering changes. Kendo UI provides built-in support for internationalization, allowing developers to create applications that can be localized to different languages and cultures.
To implement internationalization in a Kendo UI application, you need to follow these steps:
- Include the necessary Kendo UI localization files.
- Set the culture and language for the Kendo UI widgets.
- Use the Kendo UI globalization features to format dates, numbers, and currencies according to the selected culture.
Example:
<!DOCTYPE html>
<html>
<head>
<title>Kendo UI Internationalization</title>
<link rel="stylesheet" href="https://kendo.cdn.telerik.com/2023.3.1010/styles/kendo.default-v2.min.css">
<script src="https://kendo.cdn.telerik.com/2023.3.1010/js/jquery.min.js"></script>
<script src="https://kendo.cdn.telerik.com/2023.3.1010/js/kendo.all.min.js"></script>
<script src="https://kendo.cdn.telerik.com/2023.3.1010/js/cultures/kendo.culture.fr-FR.min.js"></script>
</head>
<body>
<input id="datepicker" />
<script>
// Set the culture to French
kendo.culture("fr-FR");
// Initialize the Kendo UI DatePicker with the selected culture
$("#datepicker").kendoDatePicker();
</script>
</body>
</html>
In this example, the Kendo UI DatePicker widget is initialized with the French culture. The necessary localization file for French (“kendo.culture.fr-FR.min.js”) is included, and the culture is set using the kendo.culture method. This ensures that the DatePicker widget displays dates in the French format.
8. How would you implement custom validation in a form? Provide a code example.
Custom validation in Kendo UI forms can be implemented by extending the built-in validation framework with custom rules. Kendo UI provides a flexible way to define custom validation rules that can be applied to form fields. This is particularly useful when the built-in validation rules do not meet specific requirements.
To implement custom validation, you need to define a custom validation rule and then apply it to the desired form fields. Here is an example:
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="https://kendo.cdn.telerik.com/2023.3.1010/styles/kendo.default-v2.min.css">
<script src="https://kendo.cdn.telerik.com/2023.3.1010/js/jquery.min.js"></script>
<script src="https://kendo.cdn.telerik.com/2023.3.1010/js/kendo.all.min.js"></script>
</head>
<body>
<form id="exampleForm">
<label for="username">Username:</label>
<input type="text" id="username" name="username" required data-custom-msg="Username must be 'admin'">
<button type="submit">Submit</button>
</form>
<script>
$(document).ready(function() {
// Define custom validation rule
$.extend(kendo.ui.validator.rules, {
custom: function(input) {
if (input.is("[name=username]") && input.val() !== "admin") {
return false;
}
return true;
}
});
// Define custom validation message
$.extend(kendo.ui.validator.messages, {
custom: function(input) {
return input.data("custom-msg");
}
});
// Initialize the validator
$("#exampleForm").kendoValidator().data("kendoValidator");
});
</script>
</body>
</html>
In this example, a custom validation rule is defined to check if the username is “admin”. If the validation fails, a custom message is displayed. The custom rule and message are added to the Kendo UI validator’s rules and messages, respectively.
9. Write a code snippet to perform an asynchronous data fetch and bind the result to a ListView.
To perform an asynchronous data fetch and bind the result to a ListView in Kendo UI, you can use the Kendo UI DataSource component to handle the data retrieval and the ListView component to display the data. Here is a concise example:
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="https://kendo.cdn.telerik.com/2023.3.1010/styles/kendo.default-v2.min.css">
<script src="https://kendo.cdn.telerik.com/2023.3.1010/js/jquery.min.js"></script>
<script src="https://kendo.cdn.telerik.com/2023.3.1010/js/kendo.all.min.js"></script>
</head>
<body>
<div id="listView"></div>
<script>
$(document).ready(function() {
var dataSource = new kendo.data.DataSource({
transport: {
read: {
url: "https://api.example.com/data",
dataType: "json"
}
}
});
$("#listView").kendoListView({
dataSource: dataSource,
template: "<div>#: name #</div>"
});
dataSource.read();
});
</script>
</body>
</html>
In this example, the Kendo UI DataSource is configured to fetch data asynchronously from a specified URL. The ListView is then bound to this DataSource and uses a simple template to display the data.
10. How do you make components responsive? Provide specific techniques and examples.
Responsive design ensures that web components adapt to different screen sizes and devices. Kendo UI provides several built-in features to make components responsive, such as responsive panels, grids, and media queries.
One technique is to use the Kendo UI Grid’s built-in responsiveness. The grid can automatically adjust its layout based on the screen size. Another technique is to use CSS media queries to apply different styles based on the viewport size.
Example:
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="https://kendo.cdn.telerik.com/2023.3.1010/styles/kendo.default-v2.min.css">
<script src="https://kendo.cdn.telerik.com/2023.3.1010/js/jquery.min.js"></script>
<script src="https://kendo.cdn.telerik.com/2023.3.1010/js/kendo.all.min.js"></script>
<style>
@media (max-width: 600px) {
.k-grid-header, .k-grid-content {
display: block;
width: 100%;
}
}
</style>
</head>
<body>
<div id="grid"></div>
<script>
$(document).ready(function() {
$("#grid").kendoGrid({
dataSource: {
data: [
{ name: "Jane Doe", age: 30 },
{ name: "John Smith", age: 25 }
],
pageSize: 10
},
pageable: true,
columns: [
{ field: "name", title: "Name" },
{ field: "age", title: "Age" }
],
resizable: true
});
});
</script>
</body>
</html>
In this example, the Kendo UI Grid is made responsive by using the built-in resizable feature and CSS media queries. The grid adjusts its layout based on the screen size, ensuring a better user experience on different devices.