ASP.NET

ASP.NET

2018-04-30

AJAX

AJAX

AJAX

  • AJAX = Asynchronous JavaScript And XML.
  • Update a web page without reloading the page
  • Send data to a web server - in the background
  • A browser built-in XMLHttpRequest object (to request data from a web server)

  • AJAX XML Example

  • <!DOCTYPE html>
<html>
<body>

<h2>The XMLHttpRequest Object</h2>

<button type="button" onclick="loadDoc()">Get my CD collection</button>
<br><br>
<table id="demo"></table>  

<script>
function loadDoc() {
  var xhttp = new XMLHttpRequest(); //XMLHttpRequest: AJAX主要物件，透過此物件與server端傳遞資訊
  xhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
      myFunction(this);
    }
  };
  xhttp.open("GET", "cd_catalog.xml", true);   //透過方法"GET"，給server端
  xhttp.send();
}
function myFunction(xml) {
  var i;
  var xmlDoc = xml.responseXML;  //取得xml內XML的資料
  var table="<tr><th>Artist</th><th>Title</th></tr>";
  var x = xmlDoc.getElementsByTagName("CD"); //取XML內Tag為CD
  for (i = 0; i <x.length; i++) { 
    table += "<tr><td>" +
    x[i].getElementsByTagName("ARTIST")[0].childNodes[0].nodeValue + //CD > ARTIST > Value
    "</td><td>" +
    x[i].getElementsByTagName("TITLE")[0].childNodes[0].nodeValue +  //CD > TITLE > Value
    "</td></tr>";
  }
  document.getElementById("demo").innerHTML = table;   //塞入demo內
}
</script>

</body>
</html>

    AJAX Database Example

  • <!DOCTYPE>
<html>
<body>
<form action="">
<select name="customers" onchange="showCustomer(this.value)">
<option value="" >Select</option>
<option value="ALFKI" >ALFKI </option>
<option value="NORTS" >NORTS </option>
<option value="WOLZA" >WOLZA </option>
</select>
</form>
<br>
<div id="txtHint">Customer...</div>

<script>
function showCustomer(str){
   var xhttp;
   if (str == "") {
     document.getElementById("txtHint").innerHTML="";
     return;
   }
   xhttp = new XMLHttpRequest();
   xhttp.onreadystatechange = function (){
     if (this.readyState == 4 && this.status == 200){
        document.getElementById("txtHint").innerHTML = this.responseText;
     }
   };
   xhttp.open("GET","getcustomer.asp?q="+str,true)
   xhttp.send(); 
};

</script>


</body>
</html>

     

參考網址: AJAX XML、AJAX Database

推薦網址說明: AJAX

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