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Bride of JavaScript

Bride of JavaScript. Working with JavaScript Objects and Events. Form Validation. Neonatal Feeding Study. Server-side User submits form to Web server Server validates response and returns to user if correction necessary User resubmits. Client-side

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Bride of JavaScript

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  1. Bride of JavaScript Working with JavaScript Objects and Events

  2. Form Validation • Neonatal Feeding Study

  3. Server-side User submits form to Web server Server validates response and returns to user if correction necessary User resubmits Client-side User submits form and validation is performed on user’s computer After an error correction, form is submitted. Client vs. Server Side Validation

  4. Object-based Language • Objects • Properties • Methods • [9.06]

  5. JavaScript Object Hierarchy • [9.08]-object hierarchy • window.document.REG.MEDRECNO • document.REG.MEDRECNO • [9.09]-objects in neonatal form

  6. Object Properties • [9.10]-partial list of objects and properties • object.property = expression • EXAMPLE: Changing an Object’s Value • EXAMPLE: Displaying Read Only Properties

  7. Assigning a Property to a Variable var PageColor = document.bgColor; var FrameNumber = window.length; var Browser = navigator.appName;

  8. Properties in Conditional Expressions <script language=“JavaScript”> <!--Hide from older browsers if(document.bgColor=="black") { document.fgColor="white"; } else { document.fgColor="black"; } //Stop hiding--> </script>

  9. Object Methods • [9.13-9.14]-partial list of methods -- also App. D object.method(); history.back(); form.submit(); document.write(“Thank You”); some methods use parameters (like above)

  10. The Revenge of JavaScript Managing Events

  11. Managing Events (session 8.2) • [9.15]-list of events • Event: a specific action that triggers the browser to run a block of JavaScript commands

  12. Events in Data Entry • Look at Figure 9-14 on 9.16

  13. Event Handlers • Code added to an HTML tag that is run whenever a particular event occurs.

  14. Event Handlers Syntax <HTML_tag Properties event_handler = "JavaScript Commands;"> HTML_tag = name of tag Properties = properties associated with the tag event_handler = the name of an event handler (9-15 on 9.17) JavaScript commands = function to be run

  15. Example onClick Event Handler

  16. StartForm() function StartForm() { document.REG.FORMDATE.value= DateToday(); } <body onLoad="StartForm();">

  17. function DateToday() function DateToday() { var Today=new Date(); var ThisDay=Today.getDate(); var ThisMonth=Today.getMonth()+1; var ThisYear=Today.getFullYear(); return ThisMonth+"/"+ThisDay+"/"+ThisYear; See 9.20

  18. Emulating Events(Figure 9-22, page 9.22) document.ORDERS.PRODUCT.focus(); document.ORDERS.PRODUCT.blur(); document.ORDERS.submit(); After changes--you might need to save and re-open the file. . .

  19. Working with a Selection Object • The Doctors. . . [9.24]

  20. Complete Syntax function CheckOther(){ if(document.REG.PHYSICIAN.selectedIndex==7) { document.REG.OTHERNAME.value=prompt("Enter name of physician","Name"); } document.REG.ACT.focus(); }

  21. Prompting for Input prompt("Message", "Default_text"); prompt("Enter your name", "Type name here"); Simple Input

  22. Getting the Physician's Name document.REG.OTHERNAME.value= prompt("Enter the name of physician","Name");

  23. Son of JavaScript Calculations

  24. Calculating APGAR (9.32) TOTAL = ACTIVITY + PULSE + GRIMACE + APPEARANCE + RESPIRATION <input name="act" value="0" size="1" maxlength="1" onBlur="APGAR();"> Almost the same for the other 4. . . • Gets a string and you need to calculate and verify.

  25. Converting Text to a NumberThe eval function TOTAL = eval("10"); You try: TOTAL = "10" + "5" ; TOTAL = eval("10") + eval("5");

  26. APGAR • [9.32] function APGAR() { var A = eval(document.REG.ACT.value); var P = eval(document.REG.PULSE.value); var G = eval(document.REG.GRIMACE.value); var AP = eval(document.REG.APP.value); var R = eval(document.REG.RESP.value); document.REG.TOTAL.value = A + P + G + AP + R; }

  27. Passing User Input to the Array (in the APGAR function) • The this keyword: A word reserved by JavaScript to refer to the currently selected object (field) document.REG.PULSE.value=2; would be the same as this.value=2; if the current field is the PULSE field in the form bring passed to the array.

  28. Pass Information about the Currently Selected Field to a Function <script> function SetVal(field) { field.value = 0; } </script> ------------------------------------------------------------- <input name = "PULSE" onFocus="SetVal(this);"> <input name = "RESP" onFocus="SetVal(this);">

  29. this is a tracker • The object a method is invoked through becomes the value of this. • object.method(); • we can now refer to object with this • Let's extend this to the APGAR

  30. With APGAR • You use this to pass information from the current APGAR field in the form to the APGAR function to make sure the function knows which field is currently selected. • In this manner the APGAR function knows if the user enters a 2 for Activity, a 1 for Pulse, etc.

  31. this APGAR Part of the APGAR function (in <head>): function APGAR(field) { var score = field.value; if(score==0 || score==1 || score==2) { var A = eval(document.REG.ACT.value); In the form: <input maxLength="1" name="ACT" onblur="APGAR(this);" size=1 value=0>

  32. Using this on APGAR fields <input maxLength="1" name="ACT" onblur="APGAR(this);" size="1" value="0"> <input maxLength="1" name="PULSE" onblur="APGAR(this);" size="1" value="0"> <input maxLength="1" name="GRIMACE" onblur="APGAR(this);" size="1" value="0"> <input maxLength="1" name="APP" onblur="APGAR(this);" size="1" value="0"> <input maxLength="1" name="RESP" onblur="APGAR(this);" size="1" value="0">

  33. Validating • [9.35] function APGAR(field) { var score = field.value; if(score==0 || score==1 || score==2) { var A = eval(document.REG.ACT.value); var P = eval(document.REG.PULSE.value); var G = eval(document.REG.GRIMACE.value); var AP = eval(document.REG.APP.value); var R = eval(document.REG.RESP.value); document.REG.TOTAL.value = A + P + G + AP + R; } else { alert("You must enter a 0, 1, or 2"); field.focus(); } }

  34. Notifying the User [9.37] • Alert Box alert("Message"); • Confirm confirm("Continue with Program?");

  35. Controlling Form Submission [9.39] function CheckData(){ var parents_agree=document.REG.CONSENT.checked; if(parents_agree) { alert("Form submitted successfully"); return true; } else { alert("You still need parental consent."); return false; } return parents_agree; } <form name="REG" onSubmit="return Check_Data();"> The return keyword returns a boolean

  36. Reloading a Page onClick=“location=location.href;” <input onClick="location=location.href;" type=button value="Reload Page">

  37. Complete Syntax function APGAR(field) { var score = field.value; if(score==0 || score==1 || score==2) { var A = eval(document.REG.ACT.value); var P = eval(document.REG.PULSE.value); var G = eval(document.REG.GRIMACE.value); var AP = eval(document.REG.APP.value); var R = eval(document.REG.RESP.value); document.REG.TOTAL.value = A + P + G + AP + R; if(field.name=="RESP") { document.REG.BWGT.focus(); } } else { alert("You must enter a 0, 1, or 2"); field.focus(); } }

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