15. COOKIES Javascript What are Cookies? Web Browsers and Servers use HTTP protocol to communicate and HTTP is a stateless protocol. But for a commercial website, it is required to maintain session information among different pages. For example, one user registration ends after completing many pages. But how to maintain users' session information across all the web pages. In many situations, using cookies is the most efficient method of remembering and tracking preferences, purchases, commissions, and other information required for better visitor experience or site statistics. How It Works? Your server sends some data to the visitor's browser in the form of a cookie. The browser may accept the cookie. If it does, it is stored as a plain text record on the visitor's hard drive. Now, when the visitor arrives at another page on your site, the browser sends the same cookie to the server for retrieval. Once retrieved, your server knows/remembers what was stored earlier. Cookies are a plain text data record of 5 variable-length fields: Expires: The date the cookie will expire. If this is blank, the cookie will expire when the visitor quits the browser. Domain: The domain name of your site. Path: The path to the directory or web page that set the cookie. This may be blank if you want to retrieve the cookie from any directory or page. Secure: If this field contains the word "secure", then the cookie may only be retrieved with a secure server. If this field is blank, no such restriction exists. Name=Value: Cookies are set and retrieved in the form of key-value pairs. Cookies were originally designed for CGI programming. The data contained in a cookie is automatically transmitted between the web browser and the web server, so CGI scripts on the server can read and write cookie values that are stored on the client. 82
Javascript JavaScript can also manipulate cookies using the cookie property of the Document object. JavaScript can read, create, modify, and delete the cookies that apply to the current web page. Storing Cookies The simplest way to create a cookie is to assign a string value to the document.cookie object, which looks like this. document.cookie = "key1=value1;key2=value2;expires=date"; Here the expires attribute is optional. If you provide this attribute with a valid date or time, then the cookie will expire on a given date or time and thereafter, the cookies' value will not be accessible. Note: Cookie values may not include semicolons, commas, or whitespace. For this reason, you may want to use the JavaScript escape() function to encode the value before storing it in the cookie. If you do this, you will also have to use the corresponding unescape() function when you read the cookie value. Example Try the following. It sets a customer name in an input cookie. 83
About the Tutorial JavaScript is a
Bitwise Operators .................
23. String ........................
setUTCDate () .....................
Checking for Plug-Ins .............
1. OVERVIEW Javascript What is Java
Javascript components, integrates w
Javascript This function can be use
Javascript The following example sh
Javascript JavaScript in Chrome Her
4. PLACEMENT Javascript There is a
Javascript This code will
5. VARIABLES Javascript JavaScript
Javascript Within the body of a fun
6. OPERATORS Javascript What is an
Javascript the right operand, if ye
Javascript Output (a == b) => false
Javascript Output (a && b) => fal
Javascript document.write("(a | b)
Javascript Method toSource() toStri
Javascript Output flag.toString
23. STRING Javascript The String ob
Javascript Try the following exampl
Javascript concat() indexOf() lastI
Javascript document.writeln("str.ch
Javascript Argument Details string2
Javascript lastIndexOf () This meth
Javascript var index = str1.localeC
Javascript substring. $n or $nn Whe
Javascript Search () This method ex
Javascript document.write( sliced )
Javascript Try the following exampl
Javascript Return Value Returns a s
Javascript JavaScript String toLow
Javascript var str = "Apples are r
Javascript were in a tag sup() Cau
Javascript blink () This method cau
Javascript Try the following exampl
Javascript JavaScript String font
Javascript JavaScript String link(
Javascript JavaScript String strik
Javascript JavaScript String sup(
Javascript input length prototype T
Javascript Prototype The prototype
Javascript push() reduce() reduceRi
Javascript every () Javascript arra
Javascript } var passed = [12, 5, 8
Javascript Array.prototype.filter =
Javascript } }; Example Try the fol
Javascript var len = this.length; v
Javascript join () Javascript array
Javascript var from = Number(argume
Javascript } var index = [12, 5, 8,
Javascript Array.prototype.map = fu
Javascript Its syntax is as follows
Javascript var rv = arguments[1]; }
Javascript } } throw new TypeError(
Javascript } rv = this[i--]; break;
Javascript } rv = fun.call(null, rv
Javascript Output Removed element
Javascript { } if (i in this && fun
Javascript Return Value Returns a s
Javascript toString () Javascript a
25. DATE Javascript The Date object
Javascript Return Value Returns the
Javascript Date Methods Here is a l
Javascript universal time. setUTCMo
Javascript Syntax Its syntax is as
Javascript Example Try the followin
Javascript var dt = new Date(); d
Javascript getMonth() : 11 getSecon
Javascript Syntax Its syntax is as
Javascript Try the following exampl
Javascript Output getUTCHours() :
Javascript Syntax Its syntax is as
Javascript JavaScript getYear Met
Javascript JavaScript setFullYear
Javascript If you specify a number
Javascript monthValue : An integ
Javascript setTime () Javascript da
Javascript Date.setUTCFullYear(year
Javascript document.write( dt );
Javascript Try the following exampl
Javascript Example Try the followin
Javascript var dt = new Date(1993,
Javascript toLocaleDateString () Ja
Javascript Syntax Its syntax is as
Javascript For instances of Date,
Javascript var dateobject = new
Javascript Output 743850547000 Date
Javascript minutes : An integer
Javascript In the following section
Javascript Example Try the followin
Javascript Property Value is : 0.43
Javascript JavaScript Math SQRT2 P
Javascript Try the following exampl
Javascript First Test Value : 3.141
Javascript JavaScript Math atan() M
Javascript var value = Math.atan2(+
Javascript Example Try the followin
Javascript Output First Test Value
Javascript var value = Math.log(10
Javascript min ( ) This method retu
Javascript var value = Math.pow(7,
Javascript Return Value Returns the
Javascript Output First Test Val
Javascript Example Try the followin
27. REGEXP Javascript A regular exp
Javascript Examples Following examp
Javascript m g Specifies that if th
Javascript Try the following exampl
Javascript Test1 - ignoreCase prope
Javascript if ( re.multiline ){ doc
Javascript exec ( ) The exec method
Javascript document.write("Test 2 -
Javascript document.write("Test 1 -
Javascript There are several DOMs i
Javascript forms[ ] 9 An array of F
Javascript Ex: document.close( ) op
Javascript This is main title Click
Javascript createElement( tagName)
Javascript NOTE: This example r
Javascript Specifies the loading st
Javascript NOTE: This example
Javascript Part 3: JavaScript Advan
Javascript Logical Errors Logic err
Javascript Now let us try to catch
Javascript Output Click the followi
Javascript Click the following to s
30. FORM VALIDATION Javascript Form
Javascript Basic Form Validation Fi
Javascript var emailID = document.m
Javascript Manual Animation So let'
Javascript } function moveRight(){
Javascript It is not possible to s
Javascript Output Checking for Plug
Javascript //--> If you
Javascript Error Messages in Firefo
Javascript Use a JavaScript Debugge
34. IMAGE MAP Javascript You can us
Javascript Output You can feel the
Javascript 6 plugins[] This propert
Javascript document.write(" Browser
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