The individual does the Java EE Development, works in the general company, does is the general website.
1. If you often use frameworks such as jquery to make asynchronous calls, the main thing is not to understand how jquery is used, but to understand the HTTP protocol.
2. In order to understand the HTTP protocol, you can use the Firefox console F12, Google's console F12 view Responseheader,requestheader. Under IE, you can use HttpWatch Professional this tool.
3. If you want the system to understand the native Ajax request, you can visit the website XMLHTTP Small manual http://fireyy.com/doc/xmlhttp/xmlhttprequest.html
<HTML><Head><Scripttype= "Text/javascript"> varxmlHttp; functionloadxmldoc (URL) {xmlHttp=NULL; if(window. XMLHttpRequest) {//Ie7,firefox,opear, and other browsersxmlHttp=NewXMLHttpRequest (); }Else if(window. ActiveXObject) {//Ie5,ie6 BrowserxmlHttp=NewActiveXObject ("Microsoft.XMLHTTP"); } if(XmlHttp!=NULL) {Xmlhttp.onreadystatechange=State_change; Xmlhttp.open ("GET", URLs,true); Xmlhttp.send (NULL); }Else{alert ("your browser does not support XMLHTTP"); } } //callback function called when the state changes functionState_change () {//4--Loading Complete if(Xmlhttp.readystate==4){ //--ok if(Xmlhttp.status== $) {Document.getelmentbyid ("'). InnerHTML=Xmlhttp.status; Doucment.getelmentbyid (). InnerHTML=Xmlhttp.statustext; Doucment.getelmentbyid (). InnerHTML=Xmlhttp.responsetext; }Else{alert ('the fetch data XML error status is:'+xmlhttp.statustext); } } } </Script></Head><Body> <H2>Using the HttpRequest object</H2> <P><b>Status:</b> <spanID= "A1"></span> </P> <P><b>Status text:</b> <spanID= "A2"></span> </P> <P><b>Response:</b> <BR/><spanID= "A3"></span> </P> <Buttononclick= "Loadxmldoc (' Http://www.w3school.com.cn/example/xdom/note.xml ')">Get XML</Button></Body>
XMLHTTP Small manual, native AJAX reference manual