For more information about ajax

For a simple question about ajax, please answer. The following is my complete code. Why didn't I respond after I clicked o, x, and t? the truth is that there will be more content below. do you know why? VarxmlHttp; functionxmlhttprequest () {if (window. Acti: a simple question about ajax.
The following is my complete code. Why didn't I respond after I clicked o, x, and t? the truth is that there will be more content below. do you know why?

Var xmlHttp;
Function xmlhttprequest (){

If (window. ActiveXObject ){
XmlHttp = new ActiveXObject ('Microsoft. xmlhttp ');
} Else if (window. XMLHttpRequest ){
XmlHttp = new XMLHttpRequest ();
}

}

Function funphp100 (url ){
Xmlhttprequest ();
XmlHttp. open ("GET", "for. php? Id = "+ url," true ");
XmlHttp. onreadystatechange = byphp;
XmlHttp. send (null );
}

Function byphp (){

If (xmlHttp. readyState = 1 ){
Document. getElementById ('php100'). innetHTML = "loading ......";
}

If (xmlHttp. readyState = 4 ){
If (xmlHttp. Status = 200 ){
Var byphp100 = xmlHttp. responseText;
Document. getElementById ('php100'). innetHTML = byphp100;
}
}
}


For. php


For ($ I = 1; $ I <= 6; $ I ++ ){
Echo $ I. "$ id
";
}
?>


Index. php