Dojo Interview Questions and Answers

Question: Give a sample example on Dojo.

Answer:

First you can download the dojo required files from the below link:

http://dojotutorial.org/

Example of Creating a Button

Here we are going to create a button "Hello World!". To create a button in dojo you need to a Button Widget that contains three visual states as: mouseOut, mouseOver and mouseDown. To follow the following steps for creating a dojo button widget:

dojo.require("dojo.widget.*"): It instructs you to include the dojo widget (Not load all the widgets) for managing functions.

dojo.require ("dojo.widget.Button"): This line instructs you to load the Dojo button widget. If you don't include this line, the markup code for the button would not be evaluated by Dojo upon loading, resulting in a plain HTML button instead of what you expect.

Insert the following code into the HTML body:

<button dojoType="Button" widgetId="helloDojoButton"
onClick="helloPressed();">Hello World!</button>

The key attribute of this HTML element to notice is the dojoType attribute. This is responsible for instructing Dojo on how to process the element when the page is loading. In this case you will use a button element for the button that is used to input element - Dojo will work with either as long as the dojoType attribute is present.

widgetId="helloDojoButton": This is replaced with id="helloDojoButton" without the functionality being affected - Dojo's widget system is smart enough to convert regular idattributes to widgetId's if no widgetId` attribute is explicitly named.

Connecting an Event to the Widget

When you click the command button then it doing something? We specify an onClick event handler for the given command button.

dojo.require("dojo.event.*");

Above code we use "dojo.event.*" that includes all events functionality of Dojo (But not all widgets).

Following function that will called by the button when we clicked. After clicking the "helloPressed" method is called and it displays an alert message like: "Click on the Hello World Button".

  function helloPressed()
  {
  alert('Click on the Hello World Button');
  }

Here is the code of program:

<html>
<head>
<title>button</title>
  <script type="text/javascript">
  dojo.require("dojo.event.*");
  dojo.require("dojo.widget.*");
  dojo.require("dojo.widget.Button");
  function helloPressed()
  {
  alert('Click on the Hello World Button');
  }
  function init()
  {
  var helloDojoButton = dojo.widget.byId('helloDojoButton');
  dojo.event.connect(helloDojoButton, 'onClick', 'helloPressed')
  }
  dojo.addOnLoad(init);
  </script>
</head>
<body bgcolor="#FFFFCC">
<p align="center"><font size="6" color="#800000">Welcome to Roseindia Dojo Project</font></p>
<button dojoType="Button" widgetId="helloDojoButton" onClick="helloPressed();">Hello World!</button>
<br>
</body>
</html>

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