Regular Expression continue and Cookies

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Regular Expression (continue)and Cookies
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Quick Review

• What letter values would be included for the
  following variable, which will be used for
  validation purposes
• var validCharacters /A-Z/
• a. Only A and Z would be included.
• b. Both uppercase and lowercase letters would be
  included.
• c. Only lowercase letters A-Z would be included.
• d. Only uppercase letters A-Z would be included.

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Quick Review

• What letter values would be included for the
  following variable, which will be used for
  validation purposes
• var validCharacters /A-Z/
• a. Only A and Z would be included.
• b. Both uppercase and lowercase letters would be
  included.
• c. Only lowercase letters A-Z would be included.
• d. Only uppercase letters A-Z would be included.

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Quick Review

• What object is needed to create a regular
  expression?
• a. RE
• b. RegExp
• c. RegularExp
• d. RegExpression

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Quick Review

• What object is needed to create a regular
  expression?
• a. RE
• b. RegExp
• c. RegularExp
• d. RegExpression

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Meta characters in Regular Expression(continue)

• \ / ( ) ? .
• / means the ends of regular expression
• . means any character(s)
• ton. Matches tons, tonneaus but not ton

All characters in this list need to be escaped if
we want to use them as the characters themselves
without their special meanings.
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Alternation

• choice
• Example /JohnKarenSteve/
• Group subpattern
• Example /(SamDanTom)Kat/

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Form Validation with Regular Expressions

• Check for alphabetic data (Examples first name
  or last name)
• /a-zA-Z/

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Form Validation with Regular Expressions

• Check for valid social security number
• Pattern lt3 digitsgt-lt2 digitsgt-lt4 digitsgt
• - (dash) optional
• What is the regular expression?

/d3-?\d2)-?\d4/
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Form Validation with Regular expression

• Valid phone number
• Patternlt3 digitsgtltdash and/or spacesgtlt3
  digitsgtltdash and/or spacesgtlt4 digitsgt
• Spaces optional
• What is the regular expression?

/\d3-?\s\d3)-?\s\d4/
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Form validation

• Checking for valid (format) email addresses
• _at_ username_at_address.domainname
• at least six characters
• domain name 2 characters

/((\w)\.?)_at_((\w)\.?)\.a-zA-Z2,4/
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Examples of regular expressions

• To test a string begins with letters between a
  and f (lowercase only)
• /a-f/
• To test if a string contains a number
• /0-9/
• or /\d/

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Examples of regular expressions

• To test if a string ends with three numbers
• /0-93/
• To test if 1-character string doesnt contain
  number 4 or letter a
• /a4/

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Practice

• Step 1 Change your practice in Week 10 to
  validate an international phone number in a
  function validatePhone
• 011ltspace(s)gtlt2 digitsgtltspace(s)gtlt3
  digitsgtltspace(s)gtlt5 digitsgt
• Step 2 Insert a textfield that represents a UK
  zip code. If user finishes typing and press tab
  to move to the next component, call the function
  validateUKZipCode
• Step 3 Develop the function validateUKZipCode
  for checking UK zip code. Start with one or two
  characters
• Followed by a one or two digits
• Followed by a space
• and Followed by a digit and two characters
• Example RH1 2QP
• R12 2QP

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Objectives

• Create cookies to store bits of information
• Create cookies with multiple parameters
• Read cookies and use their values
• Delete cookies when you are finished with them

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Client Side Cookies

• Cookies are text files used to store information
  about the user of your web site. Cookies commonly
  store user names and encrypted passwords for
  protected sites. They can also include items
  purchased at online stores. Many web sites store
  information to achieve a personalized page for
  the user.
• Generally any information can be stored in a
  cookie.
• Browsers since Netscape Navigator 2 and Internet
  Explorer 3 have supported the use of cookies.

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Client Side Cookies

• Cookies are written to and read from a text file
  stored on the users computer. This is
  accomplished using the cookie property of the
  document object.
• Cookies stored in Mozilla based browsers (like
  Netscape) are stored in a file called
  cookies.txt. All cookies are stored in a common
  single text file.
• Cookies stored in Internet Explorer are saved in
  a domain-specific text file. Each cookie has a
  separate text file.

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Client Side Cookies Data

• Cookies contain fields of information as shown
  below
• The domain of the server that created the cookie
• The name of the cookie
• The string of data being stored in the cookie
• The expiration date for the cookie (optional)
• A boolean value indicating whether you need a
  secure HTTP connect to access the cookie
  (optional)
• A path indicating the URL path(s) that can access
  the cookie (optional)

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Example of a real cookie

• CP
• null
• www.missworld.tv/
• 1088
• 1761935360
• 30785590
• 256242976
• 29811669

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Client Side Cookies

• Cookies can be created with or without an
  expiration date. When they are created without an
  expiration date they are considered to be
  temporary. Otherwise they are stored (persistent)
  cookies.
• A temporary cookie is valid and exists only for
  the current session of the browser. When the user
  exits the browser, the cookie is automatically
  deleted.

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Cookies attributes

• Name
• nameofcookie value
• Example name Bob
• Expiration data
• expiresWeekday, DD-MON-YY HHMMSS GMT
• Example
• expires Friday, 15-Mar-06 120000 GMT
• Domain name
• domain.domain_name
• Example
• domain.kajinsky.com

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Cookies attributes

• Path
• path pathname
• Example path /home
• Secure
• secure

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Escape and unscape() build in functions

• We can not use whitespace, semicolons, and
  commas.
• escape() function encode the string object by
  converting all non-alphanumeric characters to
  their hexadecimal equivalent, preceded by
• Unescape() converts the encoded string back to
  its original format

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Creating a Cookie with Javascript

• Cookie is stored by Javascript as a document
  object for both reading and writing cookie data
• document.cookie contains a string of namevalue
  pairs representing the names of all the cookiers
  and their corresponding values.

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Lets make a cookie
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Retrieving cookies from a server
Delete a cookie
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Client Side Cookies Security

• Most browsers do not store the information in
  cookies to the text file immediately. Often the
  information is stored in the memory of the
  computer. When you exit the browser, the cookies
  are written to file.
• For e-commerce sites two additional security
  measures are taken
• Boolean value indicating whether you need a
  secure HTTP connection
• A path indicating the URL path(s) that can access
  the cookie

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Client Side Cookies Storage Limit

• In most browsers you have a maximum of 20 cookies
  per domain. Netscape browsers have a total limit
  of 300 stored cookies.
• You should limit each cookie to a maximum length
  of 2,048 characters.

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Encoding Information Stored in Cookies

• Cookie data cannot be stored with spaces,
  semicolons, or commas you should URL encode the
  data.
• Cookies should be stored as namevalue pairs. For
  example
• userNameWilliam Stanek
• When storing the information, the escape()
  function is used. The escape function takes
  replaces non printable text characters as escape
  codes. For example, a space is stored as 20.
  When reading in the data in a cookie the
  unescape() function is used to reverse the
  encoding.

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Client Side Cookies Expiration Date and Update

• The expiration date used in a cookie is always
  formatted to Greenwich Mean time using the GMT
  method.
• var now new Date()
• expDate now.toGMTString()
• To update a cookie that has already been set,
  simply save the cookie as you did the first time
  it was created.
• document.cookie cookieInfo (where cookieInfo is
  the string of information containing the data and
  other cookie parameters)

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Extracting Data From Cookies

• Data retrieved from a cookie is a simple text
  string. While there is no specific JavaScript
  function for parsing the information from the
  text string, you can build a function using the
  indexOf() method.
• The text string returned from the cookie contains
  only the namevalue pairs of information.
• var myCookie document.cookie

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Summary

• Cookies are widely used on the WEB
• They make tracking information about the user
  practical
• There are two types of cookies
• Temporary no expiration date
• Stored future expiration date
• Deleting a cookie in JavaScript is accomplished
  by setting its expiration date to an earlier date
  than now
• Cookies can be updated
• Cookie information must be encoded using the
  escape() method and decoded using the unescape()
  method.

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Practice

• Step 1 Use the following code as your framework
  for this practice
• lthtmlgtltheadgtlttitlegtMaking a Cookielt/titlegt
• ltscript language"JavaScript"gt
• // insert your Javascvript code here
• lt/scriptgt
• lt/headgt
• ltbody gt
• lt!-- Insert your form here --gt
• lt/bodygt
• lt/htmlgt

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Practice

• Step 2 Use cookie2.htm as an example create a
  form that asks for a users favorite color
• Step 3 Also use cookie2.htm as an example,
  create a function makeCookie in which you store
  the users favorite color in a cookie
• Step 4 Test it in IE.

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Practice

• Step 4 Use cookie3.htm as an example, write a
  function to read the users favorite color from a
  cookie and set the document background to that
  color. Name this function as setBackgroundColor
• Step 5 Locate the body tag and change it to
• ltbody onLoad "javascriptsetBackground()"gt
• Step 6 Test it in IE