AJAX and PHP

Explanation of examples - HTML page

When the user types characters in the input box above, the "showHint()" function will be executed. This function is triggered by the "onkeyup" event:

<!DOCTYPE html>
 <html lang="en">
 <head>
     <script>
         function showHint(str)
         {
             if (str.length==0)
             {
                 document.getElementById("txtHint").innerHTML="";
                 return;
             }
             if (window.XMLHttpRequest)
             {
                 // IE7+, Firefox, Chrome, Opera, Safari 浏览器执行的代码
                 xmlhttp=new XMLHttpRequest();
             }
             else
             {
                 //IE6, IE5 浏览器执行的代码
                 xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
             }
             xmlhttp.onreadystatechange=function()
             {
                 if (xmlhttp.readyState==4 && xmlhttp.status==200)
                 {
                     document.getElementById("txtHint").innerHTML=xmlhttp.responseText;
                 }
             }
             xmlhttp.open("GET","gethint.php?q="+str,true);
             xmlhttp.send();
         }
     </script>
     <meta charset="UTF-8">
     <title>Title</title>
 </head>
 <body>
 
 <p><b>在输入框中输入一个姓名:</b></p>
 <form>
     姓名: <input type="text" onkeyup="showHint(this.value)">
 </form>
 <p>返回值: <span id="txtHint"></span></p>
 
 </body>
 </html>

Source code explanation:

If the input box is empty (str.length== 0), this function will clear the contents of the txtHint placeholder and exit the function.

If the input box is not empty, then showHint() will perform the following steps:

· Create an XMLHttpRequest object

· Create a function to be executed when the server response is ready

· # File

The server page called above through JavaScript is a PHP file named "gethint.php". The source code in "gethint.php" checks the name array and returns the corresponding name to the browser:

<?php
 // 将姓名填充到数组中
 $a[]="Anna";
 $a[]="Brittany";
 $a[]="Cinderella";
 $a[]="Diana";
 $a[]="Eva";
 $a[]="Fiona";
 $a[]="Gunda";
 $a[]="Hege";
 $a[]="Inga";
 $a[]="Johanna";
 $a[]="Kitty";
 $a[]="Linda";
 $a[]="Nina";
 $a[]="Ophelia";
 $a[]="Petunia";
 $a[]="Amanda";
 $a[]="Raquel";
 $a[]="Cindy";
 $a[]="Doris";
 $a[]="Eve";
 $a[]="Evita";
 $a[]="Sunniva";
 $a[]="Tove";
 $a[]="Unni";
 $a[]="Violet";
 $a[]="Liza";
 $a[]="Elizabeth";
 $a[]="Ellen";
 $a[]="Wenche";
 $a[]="Vicky";
 
 //从请求URL地址中获取 q 参数
 $q=$_GET["q"];
 
 //查找是否由匹配值， 如果 q>0
 if (strlen($q) > 0)
 {
 $hint="";
 for($i=0; $i<count($a); $i++)
 {
 if (strtolower($q)==strtolower(substr($a[$i],0,strlen($q))))
 {
 if ($hint=="")
 {
 $hint=$a[$i];
 }
 else
 {
 $hint=$hint." , ".$a[$i];
 }
 }
 }
 }
 
 // 如果没有匹配值设置输出为 "no suggestion"
 if ($hint == "")
 {
 $response="no suggestion";
 }
 else
 {
 $response=$hint;
 }
 
 //输出返回值
 echo $response;
 ?>

Explanation: If JavaScript sends any text (i.e. strlen($q ) > 0), then:

1. Find names matching the characters sent by JavaScript

2. If no match is found, set the response string to "no suggestion"

3. If one or more matching names are found, set the response string with all names

4. Send the response to the "txtHint" placeholder

Continuing Learning

new file

<!DOCTYPE html> <html lang="en"> <head> <script> function showHint(str) { if (str.length==0) { document.getElementById("txtHint").innerHTML=""; return; } if (window.XMLHttpRequest) { // IE7+, Firefox, Chrome, Opera, Safari 浏览器执行的代码 xmlhttp=new XMLHttpRequest(); } else { //IE6, IE5 浏览器执行的代码 xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); } xmlhttp.onreadystatechange=function() { if (xmlhttp.readyState==4 && xmlhttp.status==200) { document.getElementById("txtHint").innerHTML=xmlhttp.responseText; } } xmlhttp.open("GET","gethint.php?q="+str,true); xmlhttp.send(); } </script> <meta charset="UTF-8"> <title>Title</title> </head> <body> <p><b>在输入框中输入一个姓名:</b></p> <form> 姓名: <input type="text" onkeyup="showHint(this.value)"> </form> <p>返回值: <span id="txtHint"></span></p> </body> </html>

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