Server Side And Client Side Scripting — Part 1 MCQs with Explanations

Node objects that generate events (known as event emitters) define an on() method for registering handlers.

The removeAllListeners(name) is used to remove all handlers from name events represented as : emitter.removeAllListeners(name)

The on() method is used for registering handlers. addListener() is a synonym for on().

The process object is an event emitter. The Node defines other important globals under the process namespaces that contain properties of that object like version, argv, env, pid,getuid(), cwd(), chdir() and exit().

Uncaught exceptions generate events, if any handlers are registered. Otherwise, the exception just makes Node print an error and exit. process . on (" uncaughtException " , function ( e ) { console . log ( Exception, e ); }) ;

The SIGINT is a POSIX signal that generates event.

The above code snippet is used to pause data events, for throttling uploads, e.g.

The above code snippet gets “end” event fired on EOF when no more data will arrive.

The write() method never blocks. If Node cannot write the data immediately and has to buffer it internally, the write() method returns false.

Rhino is free software from Mozilla.

The spawn(f) runs f() or loads and executes file f in a new thread.

Rhino defines a handful of important global functions that are not part of core JavaScript in which readUrl(url) reads the textual contents of a URL and return as a string.

The quit() command makes Rhino exit.

Because packages and classes are represented as JavaScript objects, you can assign themto variables to give them shorter names. But you can also more formally import them, if you want to: importClass ( java . util . HashMap ) ; // Same as : var HashMap = java.util.HashMap

The output for the above code snippet is false as it is a writer and not a Reader.

Rhino allows JavaScript code to query and set the static fields of Java classes and the instance fields of Java objects. Java classes often avoid defining public fields in favor of getter and setter methods. When getter and setter methods exist, Rhino exposes them as JavaScript properties.

Just like the JavaScript classes use new operator to instantiate, so does the Java classes.

There is no natural JavaScript syntax that Rhino can extend to allow JavaScript programs to create new Java arrays, so you have to do that using the java.lang.reflect.Array class.

Node is a fast C++-based JavaScript interpreter with bindings to the low-level Unix APIs for working with processes, files, network sockets, etc., and also to HTTP client and server APIs.

Because the APIs are asynchronous, Node relies on event handlers, which are often implemented using nested functions and closures.

The node programs can be run with the command: node program.js

Use require() instead of load(). It loads and executes (only once) the named module, returning an object that contains its exported symbols.

Node defines console.log() for debugging output like browsers do.

The above code snippet says hello one second from now.

Node supports the client-side timer functions set setTimeout() , setInterval() , clearTimeout() , and clearInterval() .

Node defines other important globals under the process namespace.

Because Node’s functions and methods are asynchronous, they do not block while waiting for operations to complete.

Node objects that generate events (known as event emitters) define an on() method for registering handlers.

JavaScript can help to facilitate that experience, for example by: 1. Creating animations and other visual effects to subtly guide a user and help with page navigation 2. Sorting the columns of a table to make it easier for a user to find what she needs 3. Hiding certain content and revealing details progressively as the user “drills down” into that content

A JavaScript program can traverse and manipulate document content through the Document object and the Element objects it contains. It can alter the presentation of that content by scripting CSS styles and classes.

The JavaScript program can define the behavior of document elements by registering appropriate event handlers.

The best known advanced services is the XMLHttpRequest object, which enables networking through scripted HTTP requests.

The HTML5 specification (which, at the time of this writing, is still in draft form) and related specifications are defining a number of other important APIs for web apps. These include the data storage and graphics APIs.

All the above mentioned are advanced services.

Inline code are those that are writeen between a pair of “script” tags.

The Client-side JavaScript code is embedded within HTML documents in four ways : 1. Inline, between a pair of “script” tags 2. From an external file specified by the src attribute of a “script” tag 3. In an HTML event handler attribute, such as onclick or onmouseover 4. In a URL that uses the special javascript: protocol.

A programming philosophy known as unobtrusive JavaScript argues that content (HTML) and behavior (JavaScript code) should as much as possible be kept separate. According to this programming philosophy, JavaScript is best embedded in HTML documents using “script” elements with src attributes.

nteractive web pages that communicate with server-side CGI scripts through HTML form submissions were the original “web application” and can be written without the use of JavaScript.

The Client-side JavaScript code is embedded within HTML documents in four ways : 1. Inline, between a pair of “script” tags 2. From an external file specified by the src attribute of a “script” tag 3. In an HTML event handler attribute, such as onclick or onmouseover 4. In a URL that uses the special javascript: protocol.

JavaScript code can appear inline within an HTML file between the “script” tags.