Array Indexing-javascript

Array Indexing Arrays in JScript are sparse. That is, if you have an array with three elements that are numbered 0, 1, and 2, you can create element 50 without worrying about elements 3 through 49. If the array has an automatic length variable (see Intrinsic Objects for an explanation of automatic monitoring of array length), the length variable is set to 51, rather than to 4. You can certainly create arrays in which there are no gaps...

Read More

javascript Variable Scope

Microsoft JScript has two scopes: global and local. If you declare a variable outside of any function definition, it is a global variable, and its value is accessible and modifiable throughout your program. If you declare a variable inside of a function definition, that variable is local. It is created and destroyed every time the function is executed; it cannot be accessed by anything outside the function. A local variable can have the same...

Read More

Javascript Calendar script

Javascript Calendar script <style type="text/css"> .main { width:200px; border:1px solid black; } .month { background-color:black; font:bold 12px verdana; color:white; } .daysofweek { background-color:gray; font:bold 12px verdana; color:white; } .days { font-size: 12px; font-family:verdana; color:black; background-color: lightyellow; padding: 2px; } .days #today{ font-weight: bold; color: red; } </style> <script type="text/javascript"> function...

Read More

Validate Email address

  Checking Email  Web sites often use email addresses as usernames because they are guaranteed to be unique, as long as they are valid. In addition, the organizations can use the email addresses to communicate with their users later. You do not have to initiate a server round trip just to validate an email address, however. This task can be initiated in the client, which cancels the submission of the username to the server...

Read More

Validate a Text Field

No web developers want their Ajax applications to hit the network with requests if the users leave necessary text fields blank. Thus, checking that input elements of type text and the large boxes called textareas in HTML contain values is one of the most common forms of validation. This hack shows the code for checking if a text control is blank. The inline way of doing this is by assigning a check for the field's value in the text field's...

Read More

PHP and Javascript Variables

Variables To define a variable in PHP, you’d write:// PHP$n = 1;The equivalent in JavaScript is:// JavaScriptvar n = 1; There’s no dollar sign, just the name of the variable.  Like in PHP, you don’t define variabletypes because the type is derived from the value.  You use varfor all types. If you need a numeric type, you give your variable a  numeric value. The same appliesto booleans and strings: var n = 1;  // numbervar...

Read More

Detecting JavaScript and Cookie Compatibility

You may be expecting a huge dump of code to see if JavaScript and cookies are enabled. There ’ s no way that you ’ d want to go through with something like that at this point in the project, so the following minimalist code is offered as a decent check for JavaScript compatibility:< noscript > You will not be able to view this site if JavaScript is not enabled.Please turn on JavaScript to use this site.< /noscript >  all you need to put in your template view, and you ’ re 100 percent covered. If they don ’ t have JavaScript turned...

Read More

Javascript Array

Creating an Object We have already seen an example of an Array object being created. To create an Array object, we used the JavaScript statement var myArray = new Array(); So how is this statement made up? The first half of the statement is familiar to us. We use the var keyword to define a variable called myArray. This variable is initialized, using the assignment operator (=), to the right-hand side of the statement. The right-hand side of the statement consists of two parts. First we have the keyword new. This tells JavaScript that...

Read More

Creating a Cookie-Javascript

To make life easier for ourselves, we'll write a function that allows us to create a new cookie and set certain of its attributes with more ease. We'll look at the code first and create an example using it shortly. function setCookie(cookieName, cookieValue, cookiePath, cookieExpires) {    cookieValue = escape(cookieValue);    if (cookieExpires == "")    {       var nowDate = new Date();       nowDate.setMonth(nowDate.getMonth() + 6);       cookieExpires...

Read More

Javascript cookie string

We can set a cookie by setting document.cookie to a cookie string.  The following code will set a cookie with the UserName set as Paul,  and an expiration date of 28 December 2010. <html> <head> <script language=JavaScript>    document.cookie = "UserName=Paul;expires=Tue, 28 Dec 2010 00:00:00;"; </script> </head> <body> <p>This page just created a cookie</p> </body> </html> Save the page as FreshBakedCookie.htm. We'll see how the code works as we  discuss...

Read More

javascript Date, Time

Best seo practices How to promoting webpages Top seo tips top 10 e-commerce tips Additional seo tips Advanced seo tips Mobile seo tips Javascript Date The methods getDate(), getDay(), getMonth(), and getFullYear() allow us to retrieve date values from inside a Date object. The setDate(), setMonth(), and setFullYear() methods allow us to set the date values of an existing Date object. The getHours(), getMinutes(), getSeconds(), and getMilliseconds() methods retrieve the time values in a Date object. The setHours(),...

Read More

JavaScript Interview Questions

JavaScript Interview Questions What is the difference between == and === ? The == checks for value equality, but === checks for both type and value. difference between innerHTML and append() in JavaScript? InnerHTML is not standard, and its a String. The DOM is not, and although innerHTML is faster and less verbose, its better to use the DOM methods like appendChild(), firstChild.nodeValue, etc to alter innerHTML content. break and continue statements? Continue statement continues the current loop (if label not specified) in a new iteration...

Read More

Prototypes

Every Java-Script object has a second JavaScript object (or null, but thisis rare) associated with it. This second object is known as aprototype, and the first object inherits properties from theprototype.All objects created by object literals have the same prototypeobject, and we can refer to this prototype object in JavaScriptcode as Object.prototype. Objects created using the new keywordand a constructor invocation use the value of the prototype property of the constructor function as their prototype.So the object created by new Object() inherits...

Read More

JavaScript Timers

setTimeout() and setInterval() allow you to register a functionto be invoked once or repeatedly after a specified amountof time has elapsed. These are important global functions ofclient-side JavaScript, and are therefore defined as methods ofWindow, but they are general-purpose functions and don’treally have anything to do with the window.The setTimeout() method of the Window object schedules afunction to run after a specified number of milliseconds elapses.setTimeout() returns a value that can be passed to clearTimeout() to cancel the execution...

Read More

Retrieving the Response

A complete HTTP response consists of a status code, a set ofresponse headers, and a response body. These are availablethrough properties and methods of the XMLHttpRequestobject:• The status and statusText properties return the HTTPstatus in numeric and textual forms. These properties holdstandard HTTP values like 200 and “OK” for successfulrequests, and 404 and “Not Found” for URLs that don’tmatch any resource on the server.• The response headers can be queried with getResponseHeader() and getAllResponseHeaders().• The response body is available...

Read More

WebSocket() constructor

socket with the WebSocket() constructor:var s = new WebSocket("ws://ws.example.com/resource");The argument to the WebSocket() constructor is a URL that usesthe ws:// protocol (or wss:// for a secure connection like thatused by https://). The URL specifies the host to connect to,and may also specify a port (WebSockets use the same defaultports as HTTP and HTTPS) and a path or resource.Once you have created a socket, you generally register eventhandlers on it:s.onopen = function(e) { /* The socket is open. */ };s.onclose = function(e) { /* The socket...

Read More

concat() Method

The concat() method returns the array resulting from appending its arguments to  the array on which it was invoked. Given the script: ...

Read More

JavaScript Security

Downloading and running programs written by unknown parties is a dangerous proposition. A program available on the Web could work as advertised, but then again it could also install spyware, a backdoor into your system, or a virus, or exhibit even worse behavior such as stealing or deleting your data. The decision to take the risk of running executable programs is typically explicit; you have to download the program and assert your desire to run it by confirming a dialog box or double-clicking the program’s icon. But most people don’t...

Read More

Reserved Words in JavaScript

Reserved Words in JavaScript 1.5 >abstract else instanceof switch >boolean enum int synchronized >break export interface this byte extends long throw case false native throws catch final new transient char finally null true class float package try const for private typeof continue function protected val debugger goto public var default if return void delete implements short...

Read More

HTTP “200 OK” response

A complete request is not necessarily a successful request, andyour handler for the load event should check the status codeof the XMLHttpRequest object to ensure that you received anHTTP “200 OK” response rather than a “404 Not Found” response,...

Read More