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Web Basics ISYS546
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Basic Tools Web Server –Default directory, default home page –Virtual directory Web Page Editor –Front Page Web Languages –HTML, XML –Client-side script language: VBScript, JavaScript –Server-side language: VB.NET, ASP.NET
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Dynamic Web Pages Demo: TimeNow – – The time is now –<% –dim iHour –iHour=hour(time()) –if iHour < 12 then –response.write "good morning" –else –response.write " good afternoon " –end if –%>
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Client-Side vs Server-Side Scripting Client-side scripting: –The browser requests a page. –The server sends the page to the browser. –The browser sends the page to the script engine. –The script engine executes the script. Server-side scripting: –The browser requests a page. –The server sends the page to the engine. –The script engine executes the script. –The server sends the page to the browser. –The browser renders the page. Demo: ShowSum.htm, Web Form
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HTML Introduction Heading section –,,,, etc. Body section –,, to,, –Formatting:,,, –Comment: –List –Image –Table:, : a new row in table, : a new cell in a table row. –Form:,,,
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Webpage Editor FrontPage demo Demo: Use Response.write to write the html code generated by FrontPage.
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META Tag The meta tag allows you to provide additional information about the page that is not visible in the browser: – Redirection: – “3” is number of seconds. Demo: Redirect.htm
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TABLE Tag
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FORM Tag Form attribute: –Action: Specify the URL of a program on a server or an email address to which a form’s data will be submitted. –Method: Get: the form’s data is appended to the URL specified by the Action attribute as a QueryString. Post: A prefered method for database processing. Form’s data is sent separately from the URL. –Name: Form’s name –Target: Specified a window in which results returned from the server appear.
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QueryString A QueryString is a set of name=value pairs appended to a target URL. It can be used to pass information from one webpage to another. To create a QueryString: –Add a question mark (?) immediately after a URL. –Followed by name=value pairs separated by ampersands (&). Example: http://my.com/Target.htm?CustID=C1&Cname=Chao
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Creating a QueryString User typed URL As part of a URL specified in an anchor tag. Via a form sent to the server with the GET method. –Demo: TestReqFormQ.htm
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Client-Side Script Tag HTML and Vbscript are not case-sensitive; Javascript is case-sensitive, each statement ends in a semicolon (;).
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Script Example <!-- statements -->
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Hello World document.write (" Hello world ");
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Variable Declaraton JS:var intrate, term, amount; VB:dim intrate, term, amount Data Type: –Variant - a variable’s data type is determined when it is initialized to its first value. Variable scope: –Local: Variables declared in a function or procedure. –Global: Variables declared in the heading section, but not in a function or procedure.
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Arrays JS: var arrayName = new Array(array size); var Pet = new Array(2); Pet[0]=“dog”; Pet[1]=“cat”; Pet[2]=“bird”; VB: dim arrayName(array size) Dim Pet(2) Pet(0)=“dog” Pet(1)=“cat” Pet(2)=“bird”
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Comments JS: –Single-line comment: // –Multiple-line comments: /* … */ VB: single quotation mark ‘
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Operators Arithmetic operators: –JS: +, -, *, /, Math.pow(x,y), etc. Math is an object with many methods such as round(x), random(), sqrt(x), ceil(x), floor(x), etc. –JS: Prefix operator: ++VarName, --VarName Postfix operator: varName++, varName-- –VB:+. -, *, /, ^ Comparison operators: –JS: = =, !=,, = –VB: =, <>,, = Logical operators: –JS: &&, ||, ! –VB: AND, OR, NOT
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IF Then Statements JS:if (condition) { statements; } else { statements; } VB:if (condition) then statements else statements end if
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Case Statements JS: Switch Case Statement switch(varable name) { case value1: statements; break; case value2: statements; break; … default: statements; break; } VB: Select Case statement
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Loop Structures JS: 1.while (condition) { statements; } 2. do{ statements; } while (condition) 3.for (var I = 0; I<5;I=I+1){ statements; }
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JavaScript Build-In Objects and Methods Math object String object: In JS, a string variable is an object and can be created by: –varName = “Smith” –varName = new String(“Smith”) String object methods: – bold, fontcolor, fontsize, toLowerCase, toUpperCase – anchor (create a bookmark), link (create a link) –Substring, split (split a string into an array)
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Examples of Using String’s Methods var test = “Click Here”; var website = http://www.sfsu.edu;http://www.sfsu.edu test.link(website); var test = “one, two, three”; var newArray = test.split(“,”); Note: split is useful in parsing a queryString.
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JavaScript’s Conversion Functions toString() example: Price=5; Qty=10; Amount=Price*Qty; Document.write (Amount.toString()); Eval strVar = “5”; numVar = eval(strVar)
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JavaScript Functions Defining functions – function functionName(arg1,..,argN){ Statements; return return value; –} Note: 1. The arguments are optional. 2. The return statement is optional. A function is not required to return a value.
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VBScript Functions Defining functions: –Function functionName(arg1,..,argN) Statements functionName=returnValue –End Function –Note: Unlike VB, a function is not required to return a value.
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Browser Object Model
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Window Object The Window object represents a Web browser window. We use the properties and methods of a Window object to control browser window.
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Window Object Properties: –window.status, window.defaultstatus –window.document, window.history, window.location. –Window.name Methods: –window.open (“url”, “name”, Options) Options: menubar=no, status=no, toolbar=no, etc. –window.close –window.alert(“string”) –window.prompt(“string”) –Window.confirm() –window.prompt(“string”, “default string”) –window.focus(), window.blur() :set/remove focus –Window.setTimeout(“statements”, milliseconds)
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Document Object The document object represents the actual web page within the window. Properties: –background, bgColor, fgColor, title, url, lastModified, domain, referrer, cookie, linkColor, etc. Ex. document.bgColor=“silver”; Methods: –Document.write (“string”) –Document.open, close Demo (testDOm.htm, docProp.htm, testDoc.htm)
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Navigator Object The navigator object provides information about the browser. Properties: –Navigator.appName:browser name –Navigator.appCodeName: browser code name –Navigator.appVersion –Navigator.platform: the operating system in use.
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Location Object Allows you to change to a new web page from within a script code. Properties: –Host, hostname, pathname –Href: full URL address –Search: A URL’s queryString Methods: – location.reload() – location.replace(); replace current page and old page’s entry in the history. To open a page:location.href = “URL” Demo: TestLocation.htm
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History Object Maintain a history list of all the documents that have been opened during current session. Methods: – history.back() – history.forward() – history.go(): ex. History.go(-2) Demo: testDocOpenClose.htm
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Client-side Scripting with the Browser Object Model window.status = "Testing DOM" New Page 1 if (navigator.appName == "Netscape") { document.write("you are using Netscape!"); } else { document.write("You are using Explorer!"); } email=window.prompt("Enter email: "); window.alert ("your enail is:" + email); site=window.prompt("enter url:"); window.open (site); // document.open(); document.write("today is: " + Date()); //JavaScript is case-sensitive: Date(), not date(). email=window.prompt("Enter email: ") window.alert ("your enail is:" & email) site=window.prompt("enter url:") window.open (site) document.open() document.write("today is: " & Date())
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Testing the History Object <!-- sub clearVB() document.write ("hello, this is a new page") window.alert("Press any key to continue") document.open() document.write (" This is another new page ") document.close window.alert("Press any key to go back") history.go(-2) end sub --> New Page 1 this is old info document.write (" this is another old info ")
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Testing Location Object function openNew() site=window.prompt("enter url:") window.open (site) location.href="showformdata.htm" end function New Page 1
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HTML Tags and Events Link : click, mouseOver, mouseOut Image : abort(loading is interrupted), error, load. Area : mouseOver, mouseOut Body : blur, error, focus, load, unload Frameset: blur, error, focus, load, unload Frame: blur, focus Form: submit, reset Textbox, Text area: blur, focus, change, select Button, Radio button, check box: click List: blur, focus, change
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Event Handler Event handler name: on + event name –Ex. onClick Three ways of writing handler: –1. Within the tag –2. Event function: onCLick=“clickHandler()” –3. Event procedure as in VB. Sub button1_onCLick()
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Form Object Form Input/Select object: –Textbox, radio button, check box, drop-down list box, text area, push button, submit button, reset button. Event-Handler: –onBlur (lose focus), onCHange, onClick, onFocus, onKeyDown, onKeyPress, onKeyUp, onLoad (when a document is loaded), onMouseDown, onMouseMove, onMouseOut, onMouseOver, onMouseUp, onReset(when click the reset button), onResize(when window is resized), onSubmit. Refer an input object in a form: – document.formname.inputobjName.Value Demo: showFormData.htm
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Forms Collection The forms collection is a collection of form objects within the document object. To retrieve a form’s`property: –document.form[index].property Base 0 index –Document. formname.property
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