New Features in ASP.NET AJAX 4

Note The documentation in this section concerns ASP.NET 4 AJAX Preview 4. A more recent preview release might be available at the URL above. If so, it will include updated documentation.

The new functionality in ASP.NET AJAX enables new client data scenarios for page and component developers that enable JSON data from the server to be rendered as HTML in a highly manageable and efficient way. To enable these scenarios, ASP.NET AJAX includes the following major features:

· Client-side template rendering.

· Declarative instantiation of client-side behaviors and controls.

· Live data binding.

· Use of the observer pattern with JavaScript types.

· An AdoNetServiceProxy class for client-side interaction with ADO.NET Data Services.

· A client-side DataView control for data-bound UI in the browser.

· DataContext and AdoNetDataContext classes for interaction with Web services.

· Refactored ASP.NET AJAX framework libraries.

· Support for the DOM Ready event.

· Using JSONP to retrieve cross-domain data.

Client Template Rendering

In client-based development, templates are the most manageable way of creating UI from data. ASP.NET AJAX 4 includes a new template engine for client development that meets the following requirements:

· Performance — The engine must be able to render a typical number of items using a reasonably complex template before users perceive an interruption in their interaction with the application.

· Simplicity — The template syntax must be very readable and must be optimized for the most common scenario, namely one-way/one-time binding.

· Expression language — Templates must support an expression language to go beyond the simplest cases. The expression language should use familiar syntax, ideally JavaScript syntax.

· Interspersed code and markup — It must be possible to perform conditional rendering or to loop over markup by using code that surrounds HTML.

· Components — When using the template syntax, the developer must be able to instantiate client-side controls and behaviors that attach to HTML elements in the page or within templates.

Template Example

The following example shows a typical client template that you can create using ASP.NET AJAX 4.

<ul id="myTemplate" class="sys-template"

sys:attach="dataview"

<li>

<div>{{ Description }}</div>

</li>

</ul>

The class attribute of the outer div element is set to sys-template, which is a convention that is used in order to hide the initial template from the user. You should define this class in your CSS style sheet as {display:none;}.

When the template is rendered, it has a data item as context. Fields or properties of that data item can be included in the template markup by using {{ }} expressions — for example, {{ Name }}, if the data item has a Name field. These expressions can be placed anywhere in text content, or you can use them as the value of an attribute. In addition to fields or properties, the expression blocks can also contain any JavaScript expression that can be evaluated as a string.

You can set up DOM events by using the $addHandler method. The DOM on* attributes of elements (for example, onclick=method) also work from within templates.

Instantiating a Template by Using the DataView Control

The most convenient way to use client templates in ASP.NET AJAX 4 is through the DataView control. The content of a DataView control is used as a template that renders the data item that is provided to the control. If you set the DataView control's data property to an array, the template is rendered once for each item in the array. The DataView control binds to live data, meaning that the control is automatically updated when the data changes, without the need to rebind. This provides a dynamic data-driven UI in the browser. The following example shows the declarative markup for a DataView control that binds to an array named imagesArray.

<body xmlns:sys="javascript:Sys"

xmlns:dataview="javascript:Sys.UI.DataView"

sys:activate="*">

<ul sys:attach="dataview" class="sys-template"

dataview:data="{{ imagesArray }}"

<li>

<div>{{ Description }}</div>

</li>

</ul>

</body>

Instantiating a Template by Using Code

You can also create a compiled template from code by using the Sys.UI.Template class, as shown in the following example:

var t = new Sys.UI.Template($get("myTemplate"));

The constructor takes the parent element of the template as its argument. You can then render a compiled template into the DOM by calling its instantiateIn method and specifying an HTML container element and a data item as context. The following example shows how to do this.

t.instantiateIn(

$get("targetContainer"),

{

Name: "Name",

Description: "Description"

}

);

Using Pseudo-Columns in a Template

In addition to providing access to fields and properties of the data item, the template rendering engine also provides access to pre-defined "pseudo-columns" such as $index and $dataItem. These pseudo-columns give you access to values from the rendering engine at render time. You can use pseudo-columns the way you use any JavaScript variable in the template instance. The first example applies a different CSS class to the div element for alternating items that are rendered by the dataView control. The second examples passes the pseudo-column $dataItem, which represents the data for the current row, to a custom function named nameConvert for processing.

<span>{{nameConvert($dataItem)}}</span>

Incorporating Code into a Template by Using the code:if, code:before, and code:after Attributes

You can add the new code:if, code:before, and code:after declarative attributes to any DOM element within a template in order to render the element conditionally (code:if) or to render arbitrary code before (code:before) or after (code:after) the element. The following example shows how to use the code:If attribute to render an hr element as a separator between items. The code:if attribute uses the value of the $index pseudo-column to ensure that the hr element is rendered only between items, and not before the first one or after the last one.

<li>

<div>{{ Description }}</div>

</li>

</ul>

Posted in: asp.net | Tags: asp.net asp.net 4.0 performance feature asp.net ajax ajax dataview adonetdatacontext datacontext rendering simplicity template example

New Features in ASP.NET AJAX 4, Part 2

Instantiating Behaviors and Controls Declaratively

ASP.NET AJAX 4 introduces a way to declaratively instantiate client-side controls and behaviors and attach them to HTML elements. The declarative markup is achieved without adding any new HTML elements, simply by including additional namespaced attributes which are XHTML compliant.

Declarative Instantiation Within a Template

Suppose that you want to add a Contoso.DatePicker control to a div element. In ASP.NET AJAX 4, you can start by declaring a namespace prefix in the opening <body> tag (or in a template's parent tag), similar to the way the @ Register directive works in server-based files. The following example shows a namespace declaration.

The javascript:Sys namespace (typically mapped to the sys: prefix, as shown in the example) is used for a number of system attributes. One of those system attributes is sys:attach, which is used to specify a comma-separated list of controls or behaviors to attach to the element, as shown in the following example:

<li>

<div>{{ Description }}</div>

</li>

</ul>

The example shows how to instantiate a Contoso.DatePicker control that is attached to a div element and how to set the control's date property to the value of the CreatedDate field of the current data item.

Declarative Instantiation Outside a Template

Declarative instantiation of controls will only work if the declarative markup is within an element that has been configured, or activated, for this purpose. Templates themselves are already activated, so declarative markup to instantiate and attach controls works within a template. But to declaratively instantiate controls outside a template, you must first configure the page to ensure that sys:attach markup is within an activated element. You do this by including a sys:activate attribute on the opening body tag, and setting its value to a comma-separated list of element IDs for the elements that you want to allow declarative instantiation in. The following example activates elements whose IDs are panel1 and panel2:

This causes the ASP.NET AJAX framework to scan the children of those elements for any sys:attach attributes, and to instantiate the corresponding controls.

You can also activate every element in the document. However, doing so can cause a small delay when the page is initialized, so the technique should be used with caution on large pages. The following example shows how to activate the whole document.

A DataView control is typically attached to an element that is not already within a template. This is a common reason to use sys:activate, as in the following complete example:

<body xmlns:sys="javascript:Sys"

xmlns:dataview="javascript:Sys.UI.DataView"

sys:activate="*">

<ul sys:attach="dataview" class="sys-template"

dataview:data="{{ imagesArray }}"

<li>

<div>{{ Description }}</div>

</li>

</ul>

</body>

Live Data Binding

The template examples shown earlier include several examples of data binding that uses the one-way/one-time binding syntax: {{ expression }}. This is illustrated by the following example:

This type of binding is referred to as one-time binding because the expression is evaluated only once, at the time that the template is rendered. With one-way/one-time binding, if the source data changes after the template has been rendered (in the previous example, if the Name field changes), the rendered value will not be automatically updated.

You can use an alternative live-binding syntax in order to ensure that the target value is automatically updated whenever the source value changes. This is shown in the following example:

<h3>{binding Name}</h3>

With this binding syntax, if the Name field of the current data item is changed, the rendered value will automatically be updated in response.

This example, where the binding is to a text node (the content of the h3 element), illustrates one-way live binding. The source value (in this case, the data) binds one-way to the target (in this case, an HTML text node), so when the source value changes, the target is updated. But there is no binding from the target back to the source.

Another form of live binding is two-way live binding, which is useful when a text box is provided that enables users to modify the value of underlying data, as in the following example:

In two-way live binding, the binding works in both directions. If the target value is changed (in this case, the value in the UI), the source value is automatically updated (in this case, the underlying data item). Similarly, if the source value is changed (in this case, if the underlying data value is updated externally), the target value (the value in the UI) is updated in response. As a result, target and source are always in sync.

In the following example, if the user modifies the value in the text box, the value that is rendered in the h3 element will automatically be updated to reflect the new value that is provided by the user.

<h3>{{ binding Name }}</h3>

The live-binding syntax is similar to binding syntax in WPF (XAML). It can be used for binding between UI and data, as in the above examples, as well as directly between UI elements, between data and properties of declaratively attached controls and components, and so on. The syntax also supports additional features, such as providing functions for converting data values to rendered values, or converting back from values entered in UI to an appropriately formatted data value. The following example shows how to provide conversion functions:

A similar syntax can be used to specify a binding mode (one-way or two-way) explicitly:

However, in most cases this is not necessary, because the default binding behavior is that text boxes and other input controls automatically use two-way binding, and other bindings use one-way binding. In the previous example, this default behavior is overridden so that if the data value changes, the value in the text box will change, but if the user modifies the value in the UI, the underlying data value will not be updated correspondingly.

The underlying technology that enables live bindings is the ASP.NET AJAX observer pattern, which is used internally by the Binding class and is described in the next section. For more information about binding, see The DataView Control later in this document.

Using the Observer Pattern with JavaScript Objects and Arrays

The observer pattern enables an object to be notified about changes that occur in another object. (The term observer pattern is often misused in JavaScript frameworks to describe event handling based on the addHandler method and similar techniques.) ASP.NET AJAX 4 implements the pattern completely. It adds observer functionality to ordinary JavaScript objects or arrays so that they raise change notifications when they are modified through the Sys.Observer interface. (In the present state of JavaScript, changes that are made directly, without going through the interface, will not raise change notifications.) The observer pattern can be used to establish live bindings between UI elements and objects or arrays, such as those you might get from a JSON Web service.

In the following example, the Sys.Observer class is used to add items to the imagesArray array in a way that raises CollectionChanged notifications. As a result, the DataView control will automatically update and display the inserted item after the user has clicked the Insert button. This is possible because the DataView control is bound to its source data (in this case, the imagesArray array that the data property is set to) by using live binding.

var imagesArray = [];

Sys.Observer.makeObservable(imageArray);

function onInsert() {

var newImage = { Name: "Name", Description: "Description" };

imagesArray.add(newImage);

}

</script>

<button onclick="onInsert()">Insert</button>

<ul id="imagesList" sys:attach="dataview" class="sys-template"

dataview:data="{{ imagesArray }}"

<li>

<div>{{ Description }}</div>

</li>

</ul>

Posted in: asp.net | Tags: asp.net asp.net 4.0 asp.net ajax ajax instantiation declarative xmlns declarative instantiation javascript live data binding observer pattern

New Features in ASP.NET AJAX 4, Part 3

The DataView Control

The DataView control can bind to any JavaScript object or array, or to any ASP.NET AJAX component.

Providing Data to the DataView Control

Data can be provided to the DataView control in a number of ways. One way is by setting the data property of the DataView control. The following example shows how to set the DataView control’s data property through declarative binding:

<ul sys:attach="dataview" class="sys-template"

dataview:data="{{ imagesArray }}"

<li>

<div>{{ Description }}</div>

</li>

</ul>

The following example shows how to set the DataView control’s data property through code:

function pageLoad() {

imagesService.GetImages(querySucceeded);

}

function querySucceeded(result) {

$find("imagesList").set_data(result);

}

</script>

<li>

<div>{{ Description }}</div>

</li>

</ul>

Another way to provide data is to specify a WCF or ASP.NET Web service directly in the dataProvider property of the DataView control, as shown in the following example:

<ul sys:attach="dataview" class="sys-template"

dataview:dataprovider="../Services/imagesService.svc"

dataview:fetchOperation="GetImages"

<li>

<div>{{ Description }}</div>

</li>

</ul>

When the DataView control’s dataProvider property is set, the DataView control will use the provider (in this case, the Web service) to fetch data by using the operation specified in the fetchOperation property. For other examples in which the dataProvider property is set to an instance of the DataContext class (used for read-write scenarios) see The DataContext and AdoNetDataContext Classes later in this document.

Additional Features of the DataView Control

The DataView control provides a number of features that are not shown in the previous examples, such as support for layout templates and external templates, built-in selection support for use in master-detail scenarios, command bubbling, and so on. The following example illustrates how to use some of these features to configure linked master-detail views, using two DataView controls that are linked through live binding.

<ul sys:attach="dataview" class=" sys-template"

dataview:dataprovider="../Services/ImageService.svc"

dataview:fetchOperation="GetImages"

dataview:selecteditemclass="myselected"

dataview:sys-key="master"

</ul>

<div class="sys-template"

sys:attach="dataview"

dataview:data="{binding selectedData, source={{master}} }"

<div>Description: <input type="text" value="{binding Description}"/></div>

</div>

The Select command in the master view template ensures that when the user clicks one of the items rendered by the master view, that item becomes the selected item. As a result, the CSS class specified in the selectedItemClass property of the master DataView control is applied to the markup for that item. In addition, the corresponding data item becomes the value that is returned by the selectedData property of the master DataView control.

The detail DataView control uses live binding so that its data item is dynamically set to the current selectedData value of the master DataView control. In the example, the detail view provides an edit template with two-way binding that lets users modify the fields of the data item.

Posted in: asp.net | Tags: asp.net asp.net 4.0 asp.net ajax ajax dataview providing data

New Features in ASP.NET AJAX 4, part 4

The AdoNetServiceProxy Class

The AdoNetServiceProxy class enables read-write interaction with ADO.NET Data Services from JavaScript. The class enables access from JavaScript to a broad range of features of ADO.NET Data Services. It provides direct programmatic access to the basic REST operations provided by ADO.NET Data Services (insert, query, update, and remove), as well as many advanced features such as verb tunneling (custom HTTP methods) and optimistic concurrency.

The AdoNetServiceProxy class is used by the AdoNetDataContext class in read-write scenarios, as explained in the next section.

The DataContext and AdoNetDataContext Classes

For read-write scenarios that use Web services or data services, ASP.NET AJAX 4 provides a DataContext class that provides full support for change tracking in the browser. This enables complete end-to-end AJAX-based data scenarios.

Typically, data is fetched from the server through JSON services such as a WCF AJAX-enabled service or ADO.NET data services. The data is displayed to the user through dynamic data-driven UI, using the DataView control. Declarative live-binding markup in the template provides users with an edit UI, which enables them to modify the data. The ASP.NET AJAX DataContext class tracks all changes to the data automatically. All changes can then be sent at once to the server by calling the SaveChanges method of the DataContext class. A single DataContext instance can manage change tracking for data returned by different operations on the server, even if the operations return different types of objects.

The following example shows how to use the DataContext class.

var dataContext = new Sys.Data.DataContext();

dataContext.set_serviceUri("../Services/imagesService.svc");

dataContext.set_saveOperation("SaveImages");

dataContext.initialize();

</script>

<button onclick="dataContext.saveChanges()" class="right">Save Changes</button>

<ul sys:attach="dataview" class="sys-template"

dataview:dataprovider="{{ dataContext }}"

dataview:query="GetImages"

<li>

</li>

</ul>

If you are using an ADO.NET data service, you should use the AdoNetDataContext class instead of the more general-purpose DataContext class. (AdoNetDataContext derives from DataContext.) The AdoNetDataContext class provides additional support for features that are specific to ADO.NET, such as identity management, links and associations between entity sets that are returned in different fetch operations, hierarchical data, and optimistic concurrency.

Refactoring the Microsoft AJAX Framework Libraries

ASP.NET AJAX 4 also introduces the ability to use only parts of the ASP.NET AJAX framework for efficiency, as well as the ability to use the ScriptManager control without using the ASP.NET AJAX framework at all. The ScriptManager control provides services such as centralized management of references, support for debug and release modes, support for localization, and script combining. These services can be useful to all client-script developers, even those who use JavaScript libraries other than Microsoft AJAX, such as jQuery. Until now, the ScriptManager control included the Microsoft ASP.NET AJAX library automatically, without providing a simple way to opt out of it. As a result, when developers used the ScriptManager control in their pages, the effect was to include the whole Microsoft ASP.NET AJAX library in their applications.

In ASP.NET 4, the default behavior for the ScriptManager control is to include the complete ASP.NET AJAX library. However, the ScriptManager control supports a new MicrosoftAjaxMode property that lets you choose a subset of the framework by using only portions of the library in the form of split script files. The MicrosoftAjaxMode property can have one of the following values:

· Enabled — All Microsoft AJAX scripts are included (legacy behavior). This is the default value of the property.

· Explicit — Each split script file must be added explicitly; it is up to you to make sure that you include all scripts that have dependencies on one another.

· Disabled — All Microsoft ASP.NET AJAX script features are disabled and the ScriptManager control does not reference any scripts automatically.

When you use Explicit mode, the scripts that are available are as follows:

· MicrosoftAjaxCore.js

· MicrosoftAjaxComponentModel.js

· MicrosoftAjaxSerialization.js

· MicrosoftAjaxGlobalization.js

· MicrosoftAjaxHistory.js

· MicrosoftAjaxNetwork.js

· MicrosoftAjaxWebServices.js

· MicrosoftAjaxApplicationServices.js

· MicrosoftAjaxTemplates.js (New for ASP.NET AJAX 4)

· MicrosoftAjaxAdoNet.js (New for ASP.NET AJAX 4)

The following chart shows the dependencies between split scripts. The violet boxes that are labeled Templates (AdoNetDataContext) and Templates (DataContext) indicate that only these classes in MicrosoftAjaxTemplates.js have the indicated dependency. Thus, MicrosoftAjaxTemplates.js does not require MicrosoftAjaxWebServices.js unless you use the DataContext class, and it does not require MicrosoftAjaxAdoNet.js unless you use the AdoNetDataContext class.

The WebForms box for the MicrosoftAjaxWebForms.js script is green to indicate that it is included automatically when you set EnablePartialRendering to true (which is the default setting for the ScriptManager control).

As an example, to use the ASP.NET AJAX browser history feature with no partial rendering and with MicrosoftAjaxMode set to Explicit, the ScriptManager control must be configured as in the following example:

<asp:ScriptManager ID="ScriptManager1"

EnablePartialRendering="false"

MicrosoftAjaxMode="Explicit"

EnableHistory="true"

runat="server">

<asp:ScriptReference Name="MicrosoftAjaxCore.js" />

<asp:ScriptReference Name="MicrosoftAjaxComponentModel.js" />

<asp:ScriptReference Name="MicrosoftAjaxSerialization.js" />

<asp:ScriptReference Name="MicrosoftAjaxHistory.js" />

</Scripts>

</CompositeScript>

</asp:ScriptManager>

In the example, EnablePartialRendering has been set to false so that MicrosoftAjaxWebForms.js is not included automatically, and EnableHistory has been set to true so that the ScriptManager control can use the AJAX browser history feature. Order is important when you include split scripts — if a script has dependencies, the ScriptReference elements for those dependencies must be listed before the ScriptReference element for the script itself.

Note that split script files should be used only by developers who are concerned about optimizing for very high performance. When split script files are used, they should be used together with script combining to minimize the numbers of requests that are required in order to download the scripts.

The DOM Ready Event

In Beta 2, changes in ASP.NET make it easier to use Microsoft AJAX when you create an ASP.NET MVC application or pure client Web application. In versions earlier than Beta 2, if you wanted to use the pageLoad method outside a Web Forms application, for performance reasons you needed to call sys.application.initialize at the bottom of the page. Otherwise, the pageLoad method would not be called until the window.onload event was raised.

In Beta 2, the pageLoad method is called immediately after the document DOM content is finished loading and before the window.onload event. You no longer need to call sys.application.initialize to cause the pageLoad method to be called before window.onload occurs.

Using JSONP to Retrieve Cross-Domain Data

Ordinarily, when you make an AJAX request from a page, you are limited to making a request to the domain that hosts the page. In other words, you are not allowed to make cross-domain requests.

In Beta 2, ASP.NET AJAX includes support for JSONP. Using JSONP, you can interact with services that are located in another domain.

No special configuration is required in order to take advantage of JSONP when you create a service reference. You simply configure the service path of the service to include a reference to the target domain, as shown in the following example:

<asp:ScriptManager ID="ScriptManager1" runat="server">

<asp:ServiceReference Path="http://AnotherDomain/Books.svc" />

</Services>

</asp:ScriptManager>

In order to use JSONP to make cross-domain requests, you must interact with a JSONP-enabled service. For example, if you want to request data from a WCF service, the service must be enabled to support JSONP. For more information about how to enable JSONP for a WCF service, see the article JSON with Padding (AJAX) on the MSDN Web site.

Posted in: | Tags: asp.net asp.net 4.0 asp.net ajax ajax adonetdatacontext datacontext adonetserviceproxy ajax framework json jquery microsoftajaxglobalization microsoftajaxhistory microsoftajaxapplicationservices microsoftajaxadonet

Top 50 JavaScript & AJAX interview questions

1. Why so JavaScript and Java have similar name?

A. JavaScript is a stripped-down version of Java

B. JavaScript's syntax is loosely based on Java's

C. They both originated on the island of Java

D. None of the above

2. When a user views a page containing a JavaScript program, which machine actually executes the script?

A. The User's machine running a Web browser

B. The Web server

C. A central machine deep within Netscape's corporate offices

D. None of the above

3. ______ JavaScript is also called client-side JavaScript.

A. Microsoft

B. Navigator

C. LiveWire

D. Native

4. __________ JavaScript is also called server-side JavaScript.

A. Microsoft

B. Navigator

C. LiveWire

D. Native

5. What are variables used for in JavaScript Programs?

A. Storing numbers, dates, or other values

B. Varying randomly

C. Causing high-school algebra flashbacks

D. None of the above

6. _____ JavaScript statements embedded in an HTML page can respond to user events such as mouse-clicks, form input, and page navigation.

A. Client-side

B. Server-side

C. Local

D. Native

7. What should appear at the very end of your JavaScript?

The <script LANGUAGE="JavaScript">tag

A. The </script>

B. The <script>

C. The END statement

D. None of the above

8. Which of the following can't be done with client-side JavaScript?

A. Validating a form

B. Sending a form's contents by email

C. Storing the form's contents to a database file on the server

D. None of the above

9. Which of the following are capabilities of functions in JavaScript?

A. Return a value

B. Accept parameters and Return a value

C. Accept parameters

D. None of the above

10. Which of the following is not a valid JavaScript variable name?

A. 2names

B. _first_and_last_names

C. FirstAndLast

D. None of the above

11. ______ tag is an extension to HTML that can enclose any number of JavaScript statements.

A. <SCRIPT>

B. <BODY>

C. <HEAD>

D. <TITLE>

12. How does JavaScript store dates in a date object?

A. The number of milliseconds since January 1st, 1970

B. The number of days since January 1st, 1900

C. The number of seconds since Netscape's public stock offering.

D. None of the above

13. Which of the following attribute can hold the JavaScript version?

A. LANGUAGE

B. SCRIPT

C. VERSION

D. None of the above

14. What is the correct JavaScript syntax to write "Hello World"?

A. System.out.println("Hello World")

B. println ("Hello World")

C. document.write("Hello World")

D. response.write("Hello World")

15. Which of the following way can be used to indicate the LANGUAGE attribute?

A. <LANGUAGE="JavaScriptVersion">

B. <SCRIPT LANGUAGE="JavaScriptVersion">

C. <SCRIPT LANGUAGE="JavaScriptVersion"> JavaScript statements…</SCRIPT>

D. <SCRIPT LANGUAGE="JavaScriptVersion"!> JavaScript statements…</SCRIPT>

16. Inside which HTML element do we put the JavaScript?

A. <js>

B. <scripting>

C. <script>

D. <javascript>

17. What is the correct syntax for referring to an external script called " abc.js"?

A. <script href=" abc.js">

B. <script name=" abc.js">

C. <script src=" abc.js">

D. None of the above

18. Which types of image maps can be used with JavaScript?

A. Server-side image maps

B. Client-side image maps

C. Server-side image maps and Client-side image maps

D. None of the above

19. Which of the following navigator object properties is the same in both Netscape and IE?

A. navigator.appCodeName

B. navigator.appName

C. navigator.appVersion

D. None of the above

20. Which is the correct way to write a JavaScript array?

A. var txt = new Array(1:"tim",2:"kim",3:"jim")

B. var txt = new Array:1=("tim")2=("kim")3=("jim")

C. var txt = new Array("tim","kim","jim")

D. var txt = new Array="tim","kim","jim"

21. What does the <noscript> tag do?

A. Enclose text to be displayed by non-JavaScript browsers.

B. Prevents scripts on the page from executing.

C. Describes certain low-budget movies.

D. None of the above

22. If para1 is the DOM object for a paragraph, what is the correct syntax to change the text within the paragraph?

A. "New Text"?

B. para1.value="New Text";

C. para1.firstChild.nodeValue= "New Text";

D. para1.nodeValue="New Text";

23. JavaScript entities start with _______ and end with _________.

A. Semicolon, colon

B. Semicolon, Ampersand

C. Ampersand, colon

D. Ampersand, semicolon

24. Which of the following best describes JavaScript?

A. a low-level programming language.

B. a scripting language precompiled in the browser.

C. a compiled scripting language.

D. an object-oriented scripting language.

25. Choose the server-side JavaScript object?

A. FileUpLoad

B. Function

C. File

D. Date

26. Choose the client-side JavaScript object?

A. Database

B. Cursor

C. Client

D. FileUpLoad

27. Which of the following is not considered a JavaScript operator?

A. new

B. this

C. delete

D. typeof

28. ______method evaluates a string of JavaScript code in the context of the specified object.

A. Eval

B. ParseInt

C. ParseFloat

D. Efloat

29. Which of the following event fires when the form element loses the focus: <button>, <input>, <label>, <select>, <textarea>?

A. onfocus

B. onblur

C. onclick

D. ondblclick

30. The syntax of Eval is ________________

A. [objectName.]eval(numeric)

B. [objectName.]eval(string)

C. [EvalName.]eval(string)

D. [EvalName.]eval(numeric)

31. JavaScript is interpreted by _________

A. Client

B. Server

C. Object

D. None of the above

32. Using _______ statement is how you test for a specific condition.

A. Select

B. If

C. Switch

D. For

33. Which of the following is the structure of an if statement?

A. if (conditional expression is true) thenexecute this codeend if

B. if (conditional expression is true)execute this codeend if

C. if (conditional expression is true) {then execute this code>->}

D. if (conditional expression is true) then {execute this code}

34. How to create a Date object in JavaScript?

A. dateObjectName = new Date([parameters])

B. dateObjectName.new Date([parameters])

C. dateObjectName := new Date([parameters])

D. dateObjectName Date([parameters])

35. The _______ method of an Array object adds and/or removes elements from an array.

A. Reverse

B. Shift

C. Slice

D. Splice

36. To set up the window to capture all Click events, we use which of the following statement?

A. window.captureEvents(Event.CLICK);

B. window.handleEvents (Event.CLICK);

C. window.routeEvents(Event.CLICK );

D. window.raiseEvents(Event.CLICK );

37. Which tag(s) can handle mouse events in Netscape?

A. <IMG>

B. <A>

C. <BR>

D. None of the above

38. ____________ is the tainted property of a window object.

A. Pathname

B. Protocol

C. Defaultstatus

D. Host

39. To enable data tainting, the end user sets the _________ environment variable.

A. ENABLE_TAINT

B. MS_ENABLE_TAINT

C. NS_ENABLE_TAINT

D. ENABLE_TAINT_NS

40. In JavaScript, _________ is an object of the target language data type that encloses an object of the source language.

A. a wrapper

B. a link

C. a cursor

D. a form

41. When a JavaScript object is sent to Java, the runtime engine creates a Java wrapper of type ___________

A. ScriptObject

B. JSObject

C. JavaObject

D. Jobject

42. _______ class provides an interface for invoking JavaScript methods and examining JavaScript properties.

A. ScriptObject

B. JSObject

C. JavaObject

D. Jobject

43. _________ is a wrapped Java array, accessed from within JavaScript code.

A. JavaArray

B. JavaClass

C. JavaObject

D. JavaPackage

44. A ________ object is a reference to one of the classes in a Java package, such as netscape.javascript .

A. JavaArray

B. JavaClass

C. JavaObject

D. JavaPackage

45. The JavaScript exception is available to the Java code as an instance of __________

A. netscape.javascript.JSObject

B. netscape.javascript.JSException

C. netscape.plugin.JSException

D. None of the above

46. To automatically open the console when a JavaScript error occurs which of the following is added to prefs.js?

A. user_pref(" javascript.console.open_on_error", false);

B. user_pref("javascript.console.open_error ", true);

C. user_pref("javascript.console.open_error ", false);

D. user_pref("javascript.console.open_on_error", true);

47. To open a dialog box each time an error occurs, which of the following is added to prefs.js?

A. user_pref("javascript.classic.error_alerts", true);

B. user_pref("javascript.classic.error_alerts ", false);

C. user_pref("javascript.console.open_on_error ", true);

D. user_pref("javascript.console.open_on_error ", false);

48. The syntax of a blur method in a button object is ______________

A. Blur()

B. Blur(contrast)

C. Blur(value)

D. Blur(depth)

49. The syntax of capture events method for document object is ______________

A. captureEvents()

B. captureEvents(args eventType)

C. captureEvents(eventType)

D. captureEvents(eventVal)

50. The syntax of close method for document object is ______________

A. Close(doc)

B. Close(object)

C. Close(val)

D. Close()

Posted in: Interview Questions asp.net | Tags: client-side ajax javascript top 50 jsobject wrapper ns_enable_taint javaarray javaclass blur web browser navigator livewire

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