AJAX 使用範例 @ cww20811ss的部落格

function showUser(str)

{

if (window.XMLHttpRequest)

{// code for IE7+, Firefox, Chrome, Opera, Safari

xmlhttp=new XMLHttpRequest();

}

else

{// code for IE6, IE5

xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");

}

xmlhttp.onreadystatechange=function()

{

if (xmlhttp.readyState==4 && xmlhttp.status==200)

{

//document.getElementById("txtHint").innerHTML=xmlhttp.responseText;

}

var postString = "sn_id="+str+'&content='+str+'ddd';

xmlhttp.open("POST","./stickynote_edit.php",true);

xmlhttp.setRequestHeader("Content-type","application/x-www-form-urlencoded");

xmlhttp.send(postString);

}

</script>

Send a Request To a Server

To send a request to a server, we use the open() and send() methods of the XMLHttpRequest object:

xmlhttp.open("GET","ajax_info.txt",true);

xmlhttp.send();

Method

Description

open(method,url,async)

Specifies the type of request, the URL, and if the request should be handled asynchronously or not.

method: the type of request: GET or POST

url: the location of the file on the server

async: true (asynchronous) or false (synchronous)

send(string)

Sends the request off to the server.

string: Only used for POST requests

To get the response from a server, use the responseText or responseXML property of the XMLHttpRequest object.

Property	Description
responseText	get the response data as a string
responseXML	get the response data as XML data

When a request to a server is sent, we want to perform some actions based on the response.

The onreadystatechange event is triggered every time the readyState changes.

The readyState property holds the status of the XMLHttpRequest.

Three important properties of the XMLHttpRequest object:

Property	Description
onreadystatechange	Stores a function (or the name of a function) to be called automatically each time the readyState property changes
readyState	Holds the status of the XMLHttpRequest. Changes from 0 to 4: 0: request not initialized 1: server connection established 2: request received 3: processing request 4: request finished and response is ready
status	200: "OK" 404: Page not found