1. 1 CS 21A Beginning JavaScript Programming Project 2 Creating Pop-up Windows, Adding Scrolling Messages, and Validating Forms Sonny Huang

2. 2 Project 2 Creating Pop-up Windows, Adding Scrolling Messages, and Validating Forms Outline Explain the four basic components of a scrolling message Write a user-defined function to display a scrolling message in a form text box Describe the If statement Define conditionals and discuss the conditional operands Define recursion Describe the focus() method Write a user-defined function to calculate mortgage payments Validate data entry using a nested If…Else statement Describe the parseInt(), parseFloat(), and isNaN() built-in functions

3. 3 Project 2 Creating Pop-up Windows, Adding Scrolling Messages, and Validating Forms Describe the math pow() method Write a user-defined function to format output in currency format Discuss For and While loops Use the open() method to display another Web page in a pop-up window Use the lastModified property to display the date a Web page was last modified

4. 4 Introduction  Introduction We will create a Web page that will allow Home Finders Nationwide Realty customers to calculate the amount of their monthly mortgage payment, based on the amount of mortgage, interest rate, and the number of years. We will learn 1. how to add a scrolling message, which will introduce them to the substring() method and the If statement. 2.how to use JavaScript to validate forms.

5. 5 Introduction 3.If…Else statements, the parseInt(), parseFloat(), and isNaN() built-in functions, as well as using the pow() method. 4. writing functions to calculate and display the resulting monthly payment amount using the currency format. 5. how to add a pop-up window to display information on using the mortgage payment calculator.

6. 6 Introduction We all experienced using the Internet to purchase or searching something. Look for this web site homeadvisor.msn.com and other online lenders and realtors. Do you search for a house online? How do you feel about applying for loans online? What are the important issues?

7. 7 Project Two — Home Finders Nationwide Realty We want to design a web page first loads a pop up windows to displays a message informing users of the new mortgage payment calculator.

8. 8 Project Two — Home Finders Nationwide Realty The web page also includes a scrolling message that constantly displays to remind visitors of the current low mortgage rate.

9. 9 Project Two — Home Finders Nationwide Realty The mortgage payment form allows users to calculate their monthly payment based on the amount of mortgage, interest rate, and years.

10. 10 Project Two — Home Finders Nationwide Realty We will use functions to validate data, calculate monthly payment, and display the result in currency format. For the sense of up to date, we will have the last modification date displayed at the bottom of the page.

11. 11 Project Two — Home Finders Nationwide Realty Data Validation Requirement: If the information inputted is not a number or not a valid form than we should use the alert message box to notify the user and position the insertion point in the appropriate text box. When all the entries are valid, the calculation function will be called to provide the monthly payment information.

12. 12 Project Two — Home Finders Nationwide Realty Calculations: The formula for calculating a monthly payment is Monthly payment = loan * rate (1-(1/(1+rate) payments ))

13. 13 Project Two — Home Finders Nationwide Realty Starting Notepad and opening the home.htm file

14. 14 Inserting a scrolling message on a Web page Microsoft create marquee html tag. creates a scrolling display and is an MSIE extension and will probably never be supported by any other browser. The basic use of is simple. Put most any kind of markup between and. Hi There!

15. 15 Inserting a scrolling message on a Web page By using a JavaScript user defined function can create the scrolling effect as marquee and can compatible with all the browsers. A scrolling message has four basic components: 1. The display object defines where the scrolling object displays(status bar, or form text box). 2. The message is a text string assigned to a variable. 3. The position is the starting location in which the message first displays in the display object. 4. The delay is the length of time between when a message ends and when it starts to appear again.

16. 16 Inserting a scrolling message on a Web page Using the form’s text box to create the scrolling effect. Form: An HTML form is a section of a document containing normal content, markup, special elements called controls (checkboxes, radio buttons, menus, etc.), and labels on those controls. Users generally "complete" a form by modifying its controls (entering text, selecting menu items, etc.), before submitting the form to an agent for processing (e.g., to a Web server, to a mail server, etc.)

17. 17 Inserting a scrolling message on a Web page Input(one of the form’s control types): We could create two types of controls that allow users to input text. The INPUT element creates a single-line input control and the TEXTAREA element creates a multi-line input control. Input tag’ Attribute definitions type = text This attribute specifies the type of control to create. The default value for this attribute is "text". name = name This attribute assigns the control name.

18. 18 Inserting a scrolling message on a Web page size = number This attribute tells the user agent the initial width of the control. The width is given in pixels except when type attribute has the value "text" or "password". In that case, its value refers to the (integer) number of characters.

19. 19 Inserting a scrolling message on a Web page Creating a form text box to display a scrolling message: Inserting the code in the section

20. 20 Inserting a scrolling message on a Web page

21. 21 Inserting a scrolling message on a Web page Creating a user-defined function for a scrolling message We will create function scrollingMsg() to perform 1. Assign message. 2. Check the end of the message. 3. It assigns the next character in the message to the textbox. The function requires three variables: var scrollMsg = "Mortgage rates are at their LOWEST!" var msgSpace = "--- ---" var beginPos = 0

22. 22 Inserting a scrolling message on a Web page Put <!--Hide from old browsers var scrollMsg = "Mortgage rates are at their LOWEST!" var msgSpace = "--- ---" var beginPos = 0 after the Title tab.

23. 23 Inserting a scrolling message on a Web page

24. 24 Inserting a scrolling message on a Web page Put the the user define function, scrollingMsg(), after the variable declaration. function scrollingMsg() { document.msgForm.scrollingMsg.value = scrollMsg.substring(beginPos,scrollMsg.length)+msgSpa ce+scrollMsg.substring(0,beginPos)

25. 25 Inserting a scrolling message on a Web page The scrollMsg and msgSpace are concatenated and assigned to the scrollingMsg text box through the following statement document.msgForm.scrollingMsg.value = scrollMsg.substring(beginPos,scrollMsg.length)+msgSpa ce+scrollMsg.substring(0,beginPos) Mortgage rates are at their LOWEST! --- ---

26. 26 Inserting a scrolling message on a Web page The form, msgForm, becomes property of document object. The text box, scrollingMsg, become property of document.msgForm object. The property value is the property of document.msgForm.scrollingMsg.

27. 27 Inserting a scrolling message on a Web page Increment the Position Locator Variable beginPos = beginPos + 1

28. 28 Inserting a scrolling message on a Web page Entering an If Statement

29. 29 Inserting a scrolling message on a Web page if (condition) { statements1 } else { statements2 } The condition can be any JavaScript expression that evaluates to true or false. The statements to be executed can be any JavaScript statements, including further nested if statements. If you want to use more than one statement after an if or else statement, you must enclose the statements in curly braces, {}.

30. 30 Inserting a scrolling message on a Web page

31. 31 Inserting a scrolling message on a Web page

32. 32 Inserting a scrolling message on a Web page Example. In the following example, the function checkData returns true if the number of characters in a Text object is three; otherwise, it displays an alert and returns false. function checkData () { if (document.form1.threeChar.value.length == 3) { return true } else { alert("Enter exactly three characters. “ + document.form1.threeChar.value + " is not valid.") return false } }

33. 33 Inserting a scrolling message on a Web page If the beginning position is greater than the message length then set the beginning position to zero. beginPos = beginPos + 1 if (beginPos > scrollMsg.length) { beginPos = 0 }

34. 34 Inserting a scrolling message on a Web page If the beginning position is greater than the message length then set the beginning position to zero. beginPos = beginPos + 1 if (beginPos > scrollMsg.length) { beginPos = 0 }

35. 35 Using the setTimeout() Method to create a Recursive Function Call Recursion A programming method in which a routine calls itself. Recursion is an extremely powerful concept, but it can strain a computer's memory resources Using the setTimeout function to call itself to create Scrolling Effect. window.setTimeout("scrollingMsg()",200)

36. 36 Using the setTimeout() Method to create a Recursive Function Call

37. 37 Using the setTimeout() Method to create a Recursive Function Call Adding an Event Handler We will place an onload() even handler in the tag to create the scrolling message when the web page is load.

38. 38 Using the setTimeout() Method to create a Recursive Function Call

39. 39 Using the setTimeout() Method to create a Recursive Function Call Insert the following statement

40. 40 Saving the HTML file and Testing the page

41. 41 The Mortgage Payment Calculator Form To Assign a value to a text box object within a form, we need to use the form name, the text box name and the value attribute.

42. 42 The Mortgage Payment Calculator Form Inserting an Event Handler in an Anchor Tag A link is a connection from one Web resource to another. Although a simple concept, the link has been one of the primary forces driving the success of the Web. A link has two ends -- called anchors -- and a direction. The link starts at the "source" anchor and points to the "destination" anchor, which may be any Web resource (e.g., an image, a video clip, a sound bite, a program, an HTML document, an element within an HTML document, etc.).

43. 43 The Mortgage Payment Calculator Form An anchor name is the value of either the name or id attribute when used in the context of anchors. Anchor names must observe the following rules:  Uniqueness: Anchor names must be unique within a document. Anchor names that differ only in case may not appear in the same document.  String matching: Comparisons between fragment identifiers and anchor names must be done by exact (case-sensitive) match.

44. 44 The Mortgage Payment Calculator Form Thus, the following example is correct with respect to string matching and must be considered a match by user agents:......more document......

45. 45 The Mortgage Payment Calculator Form We will use the onclick event handler within the tag to triger a user defined function, doMort(). The doMort() function will clear the text box and place the insertion point in the Amount Mortgage box. In an Html file the following statement should match with each other. Estimate Mortgage Payment

46. 46 The Mortgage Payment Calculator Form

47. 47 The Mortgage Payment Calculator Form

48. 48 Writing the doMort() User-Defined Function We will use the onclick event handler within the tag to triger a user defined function, doMort(). The doMort() function will clear the text box and place the insertion point in the Amount Mortgage box. In an Html file the following statement should match with each other. Estimate Mortgage Payment

49. 49 Writing the doMort() User-Defined Function focus Method. Gives focus to the specified object. Syntax 1. fileUploadName.focus() 2. passwordName.focus() 3. selectName.focus() 4. textName.focus() 5. textareaName.focus() 6. frameReference.focus() 7. windowReference.focus()

50. 50 Writing the doMort() User-Defined Function Parameters fileUploadName is either the value of the NAME attribute of a FileUpload object or an element in the elements array. passwordName is either the value of the NAME attribute of a Password object or an element in the elements array. selectName is either the value of the NAME attribute of a Select object or an element in the elements array.

51. 51 Writing the doMort() User-Defined Function textName is either the value of the NAME attribute of a Text object or an element in the elements array. textareaName is either the value of the NAME attribute of a Textarea object or an element in the elements array. frameReference is a valid way of referring to a frame.

52. 52 Writing the doMort() User-Defined Function function doMort() { document.MortCalc.Amount.value=" " document.MortCalc.Rate.value=" " document.MortCalc.Years.value=" " document.MortCalc.Payment.value=" " document.MortCalc.Amount.focus() }

53. 53 Writing the doMort() User-Defined Function

54. 54 Writing the doMort() User-Defined Function

55. 55 Validating the Mortgage Payment Calculator Form

56. 56 Validating the Mortgage Payment Calculator Form Validating Data Using the If… Else Statement

57. 57 Validating the Mortgage Payment Calculator Form

58. 58 Validating the Mortgage Payment Calculator Form Using the indentation and braces({ })in the if…else statement will improve the readability.

59. 59 Validating the Mortgage Payment Calculator Form Validating Data Criteria Using Built-in Functions JavaScript accepts data entered into a text box as string data. If we want to using the information to do mathematics and comparison, we have to convert the values to a proper data type.  eval attempts to evaluate a string representing any JavaScript literals or variables, converting it to a number.  parseInt converts a string to an integer of the specified radix (base), if possible.

60. 60 Validating the Mortgage Payment Calculator Form  parseFloat converts a string to a floating-point number, if possible.  The isNaN function evaluates an argument to determine if it is "NaN" (not a number).

61. 61 Validating the Mortgage Payment Calculator Form

62. 62 Validating the Mortgage Payment Calculator Form We use the Calc() user defined function to convert and store the information inputted.

63. 63 Validating the Mortgage Payment Calculator Form Validate moreAmount

64. 64 Validating the Mortgage Payment Calculator Form Validate moreRate

65. 65 Validating the Mortgage Payment Calculator Form Validate moreYears

66. 66 Validating the Mortgage Payment Calculator Form

67. 67 Validating the Mortgage Payment Calculator Form Adding an Event Handler to Call a Function

68. 68 Validating the Mortgage Payment Calculator Form Testing the Web page

69. 69 Validating the Mortgage Payment Calculator Form

70. 70 Determining the Monthly Payment After validating all the inputted information, we want to use the information to generate the monthly payment. We will define a function monthly() which pass in mortAmount, mortRate, and mortYears to the function and return a monthly payment. The return information will assignment to document.MortCalc.Payment.value. So, we will insert the following statement in the Calc() function. document.MortCalc.Payment.value=monthly(mortAmou nt,mortRate,mortYears)

71. 71 Determining the Monthly Payment

72. 72 Determining the Monthly Payment Creating the monthly() Function The formula to calculate the monthly payment of a loan is : Monthly Interest Rate(MIR) Loan Amount * ( ) 1 (1-( ) (1 + MIR) payments

73. 73 Determining the Monthly Payment Creating the monthly() Function The formula to calculate the monthly payment of a loan is : Monthly Interest Rate(MIR) Loan Amount * ( ) 1 (1-( ) (1 + MIR) payments

74. 74 Determining the Monthly Payment Math.pow() method We will use Math.pow() method to calculate the (1 + MIR) payments.

75. 75 Determining the Monthly Payment The whole function should look like the following:

76. 76 Determining the Monthly Payment

77. 77 Determining the Monthly Payment

78. 78 Formatting the Monthly Payment Output as Currency There are five steps we need to go through to format the currency: 1). Take the monthly payment dollar string value and separate the dollars from the cents based on the position of the decimal point. 2). Using the indexOf() method to determine the decimal point location. 3). Separate the value to dollar amount and cents amount by using the decimal point.

79. 79 Formatting the Monthly Payment Output as Currency 4). Insert commas to the dollar amount for every three position. 5). Insert a dollar sign at the beginning of the string and concatenate it with the dollar amount, a decimal point and two digits of cents information and return the value.

80. 80 Formatting the Monthly Payment Output as Currency We put these steps into a function called dollarFormat(). This function need to pass in an argument, monthly payment amount, and will return a structured currency format. function dollarFormat(valuein)

81. 81 Formatting the Monthly Payment Output as Currency indexOf Method. Returns the index within the calling String object of the first occurrence of the specified value, starting the search at fromIndex. Syntax stringName.indexOf(searchValue, [fromIndex]) Parameters stringName is any string or a property of an existing object. searchValue is a string or a property of an existing object, representing the value to search for.

82. 82 Formatting the Monthly Payment Output as Currency fromIndex is the location within the calling string to start the search from. It can be any integer from zero to stringName.length - 1 or a property of an existing object. Description Characters in a string are indexed from left to right. The index of the first character is zero, and the index of the last character is stringName.length - 1. If you do not specify a value for fromIndex, JavaScript assumes zero by default. If searchValue is not found, JavaScript returns -1.

83. 83 Formatting the Monthly Payment Output as Currency If stringName contains an empty string (""), indexOf returns an empty string. The indexOf method is case sensitive. For example, the following expression returns -1: "Blue Whale".indexOf("blue") Example var anyString="Brave new world" //Displays 8 document.write(" The index of the first w from the beginning is " + anyString.indexOf("w"))

84. 84 Formatting the Monthly Payment Output as Currency //Displays 6 document.write(" The index of 'new' from the beginning is " + anyString.indexOf("new"))

85. 85 Formatting the Monthly Payment Output as Currency

86. 86 Formatting the Monthly Payment Output as Currency Determining the Dollars Portion

87. 87 Formatting the Monthly Payment Output as Currency for loop A for loop repeats until a specified condition evaluates to false. The JavaScript for loop is similar to the Java and C for loop. A for statement looks as follows: for ([initial-expression]; [condition]; [increment- expression]) { statements }

88. 88 Formatting the Monthly Payment Output as Currency When a for loop executes, the following occurs: 1.The initializing expression initial-expression, if any, is executed. This expression usually initializes one or more loop counters, but the syntax allows an expression of any degree of complexity. 2.The condition expression is evaluated. If the value of condition is true, the loop statements execute. If the value of condition is false, the for loop terminates.

89. 89 Formatting the Monthly Payment Output as Currency 3. The update expression increment-expression executes. 4. The statements execute, and control returns to step 2. Example. The following function contains a for statement that counts the number of selected options in a scrolling list (a Select object that allows multiple selections). The for statement declares the variable i and initializes it to zero.

90. 90 Formatting the Monthly Payment Output as Currency It checks that i is less than the number of options in the Select object, performs the succeeding if statement, and increments i by one after each pass through the loop. function howMany(selectObject) { var numberSelected=0 for (var i=0; i

91. 91 Formatting the Monthly Payment Output as Currency

92. 92 Formatting the Monthly Payment Output as Currency

93. 93 Formatting the Monthly Payment Output as Currency while statement A while statement repeats a loop as long as a specified condition evaluates to true. A while statement looks as follows: while (condition) { statements } If the condition becomes false, the statements within the loop stop executing and control passes to the statement following the loop.

94. 94 Formatting the Monthly Payment Output as Currency The condition test occurs only when the statements in the loop have been executed and the loop is about to be repeated. That is, the condition test is not continuous but is performed once at the beginning of the loop and again just following the last statement in statements, each time control passes through the loop. Example. The following while loop iterates as long as n is less than three: n = 0 x = 0 while( n < 3 ) { n ++ x += n }

95. 95 Formatting the Monthly Payment Output as Currency

96. 96 Formatting the Monthly Payment Output as Currency Extracting the Dollars Portion and Inserting Commas

97. 97 Formatting the Monthly Payment Output as Currency Extracting the Cents Portion and Defining the Decimal Amount substring Method. Returns a subset of a String object. Syntax stringName.substring(indexA, indexB) Parameters stringName is any string or a property of an existing object.

98. 98 Formatting the Monthly Payment Output as Currency indexA is any integer from zero to stringName.length - 1, or a property of an existing object. indexB is any integer from zero to stringName.length, or a property of an existing object. Method of String

99. 99 Formatting the Monthly Payment Output as Currency Description Characters in a string are indexed from left to right. The index of the first character is zero, and the index of the last character is stringName.length - 1.  If indexA is less than indexB, the substring method returns the subset starting with the character at indexA and ending with the character before indexB.  If indexA is greater than indexB, the substring method returns the subset starting with the character before indexB and ending with the character at indexA.  If indexA is equal to indexB, the substring method returns the empty string.

100. 100 Formatting the Monthly Payment Output as Currency Examples The following examples use substring to display characters from the string "Netscape": var anyString="Netscape" //Displays "Net" document.write(anyString.substring(0,3)) document.write(anyString.substring(3,0)) //Displays "cap" document.write(anyString.substring(4,7)) document.write(anyString.substring(7,4))

101. 101 Formatting the Monthly Payment Output as Currency //Displays "Netscap" document.write(anyString.substring(0,7)) //Displays "Netscape" document.write(anyString.substring(0,8)) document.write(anyString.substring(0,10))

102. 102 Formatting the Monthly Payment Output as Currency Extracting the Cents Portion and Defining the Decimal Amount

103. 103 Formatting the Monthly Payment Output as Currency Reconstructing the Formatted Output and Returning the Formatted Value

104. 104 Formatting the Monthly Payment Output as Currency

105. 105 Formatting the Monthly Payment Output as Currency Passing the Monthly Payment Value to the dollarFormat() Function

106. 106 Formatting the Monthly Payment Output as Currency

107. 107 Adding a Pop-up Window Except alert and confirm message boxes, we can use JavaScript (window object ‘s open())to open another HTML file to create a pop-up window.

108. 108 Adding a Pop-up Window open()’s attributes.

109. 109 Adding a Pop-up Window

110. 110 Adding a Pop-up Window

111. 111 Adding a Pop-up Window Adding the Date Last Modified