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PHP Learning 4-php and Ajax

Source: Internet
Author: User
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1. Create a XMLHttpRequest Object

 1  var  xmlhttp= null  2  if  (Window. XMLHttpRequest) { 3  xmlhttp=new  XMLHttpRequest () //  4  }   5  else  if  (Window.activexobject) { 6  xmlhttp= new  ActiveXObject ("Microsoft.XMLHTTP") // // Apply Internet Expoler  7 }

2. PHP uses AJAX instances

(1) Write an HTML form. It contains a simple HTML form and a link to JavaScript

123<script src= "Clienthint.js" ></script>45 6<body>7 8<form>9First Name:Ten<input type= "text" id= "Txt1" OneOnkeyup= "Showhint (this.value)" >//an event is triggered when the user presses and releases the key in the input field A //When the event is triggered, a function named Showhint () is executed -</form> -  the<p>suggestions: <span id= "Txthint" ></span></p> - //below the form is a <span> named "Txthint". It is used as a placeholder for the data returned by the Showhint () function.  -</body> -
(2) The JavaScript code is stored in the "clienthint.js" file, which is linked to the HTML document
1 varxmlHttp2 functionShowhint (str)//each time a character is entered in the input field, the function is executed once. 3 {4 if(str.length==0)5   { 6document.getElementById ("Txthint"). Innerhtml= ""7   return8   }9xmlhttp=Getxmlhttpobject ()Ten if(xmlhttp==NULL) One   { AAlert ("Browser does not support HTTP Request") -   return -   }  the varUrl= "gethint.php"//define the URL (file name) to send to the server -url=url+ "? q=" +str//Add the parameter (q) with the input field contents to this URL -url=url+ "&sid=" +math.random ()//add a random number to prevent the server from using cached files -Xmlhttp.onreadystatechange=statechanged//Call the Getxmlhttpobject function to create a XMLHTTP object and tell the object to execute a function named StateChanged when the event is triggered +Xmlhttp.open ("GET", URL,true)//Opens the XMLHTTP object with the given URL. -Xmlhttp.send (NULL)//sending an HTTP request to the server + }  A  at functionStateChanged ()//The function is executed whenever the state of the XMLHTTP object changes.  - {  - if(xmlhttp.readystate==4 | | xmlhttp.readystate== "COMPLETE") - //fills the contents of the Txthint placeholder Txthint with the response text when the State becomes 4 (or "complete").  -  {  -document.getElementById ("Txthint"). Innerhtml=xmlhttp.ResponseText in  }  - } to  + functionGetxmlhttpobject ()//resolves an issue that creates different XMLHTTP objects for different browsers.  - { the varxmlhttp=NULL; * Try $  {Panax Notoginseng  //Firefox, Opera 8.0+, Safari -xmlhttp=NewXMLHttpRequest (); the  } + Catch(e) A  { the  //Internet Explorer +  Try -   { $xmlhttp=NewActiveXObject ("Msxml2.xmlhttp"); $   } -  Catch(e) -   { thexmlhttp=NewActiveXObject ("Microsoft.XMLHTTP"); -   }Wuyi  } the returnxmlHttp; -}
(3) The server page called by JavaScript code is a simple server page called "gethint.php".
The code in "gethint.php" checks the name array and returns the corresponding name to the client:
1<?PHP2 //Fill up array with names3 $a[]= "Anna";4 $a[]= "Brittany";5 $a[]= "Cinderella";6 $a[]= "Diana";7 $a[]= "Eva";8 $a[]= "Fiona";9 $a[]= "Gunda";Ten $a[]= "Hege"; One $a[]= "Inga"; A $a[]= "Johanna"; - $a[]= "Kitty"; - $a[]= "Linda"; the $a[]= "Nina"; - $a[]= "Ophelia"; - $a[]= "Petunia"; - $a[]= "Amanda"; + $a[]= "Raquel"; - $a[]= "Cindy"; + $a[]= "Doris"; A $a[]= "Eve"; at $a[]= "Evita"; - $a[]= "Sunniva"; - $a[]= "Tove"; - $a[]= "Unni"; - $a[]= "Violet"; - $a[]= "Liza"; in $a[]= "Elizabeth"; - $a[]= "Ellen"; to $a[]= "Wenche"; + $a[]= "Vicky"; -  the //get the Q parameter from URL * $q=$_get["Q"]; $ Panax Notoginseng //Lookup all hints from array if length of q>0 - if(strlen($q) > 0) the { + $hint=""; A  for($i= 0;$i<Count($a);$i++) the   { +   if(Strtolower($q)==Strtolower(substr($a[$i],0,strlen($q)))) -     { $     if($hint=="") $       { -       $hint=$a[$i]; -       } the     Else -       {Wuyi       $hint=$hint." , ".$a[$i]; the       } -     } Wu   } - } About  $ //Set output to "no suggestion" if no hint were found - //or to the correct values - if($hint== "") - { A $response= "No Suggestion"; + } the Else - { $ $response=$hint; the } the  the //Output The response the Echo $response; -?>
(* organized from W3school)
PHP Learning 4-php and Ajax

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