hacks_2_4.js

Ajax.Hacks,快来看啊

var formObj = null;
var formObjTyp = "";
var request=null;
//input field's event handlers
window.onload=function(){
    var sts = document.getElementById("sts");
    if(sts != null){
        sts.onblur=function(){getSelectInfo(this); };  }

    var eur = document.getElementById("euro");
    if(eur != null){
        eur.onclick=function(){generateList(this);  };}
     var southa = document.getElementById("southam");
    if(southa != null){
        southa.onclick=function(){generateList(this);  };}
}

function generateList(obj){
    if (obj == null ) { return; }
    if(obj.checked) {
        formObj=obj;
        formObjTyp =formObj.tagName.toLowerCase();
        var url = "http://www.parkerriver.com/s/selectl?countryType="+
                  encodeURIComponent(obj.value);
        httpRequest("GET",url,true);
    }
}

function getSelectInfo(selectObj){
    if (selectObj == null) { return; }
    formObj=selectObj;
    formObjTyp =formObj.tagName.toLowerCase();
    var optsArray = formObj.options;
    var selectedArray = new Array();
    var val = "";
    for(var i=0,j=0; i < optsArray.length; i++){
        if(optsArray[i].selected) {
            selectedArray[j]=optsArray[i].value;
            j++;
        }

    }
    for(var k = 0; k < selectedArray.length; k++){
        if(k !=selectedArray.length-1 ) { val +=selectedArray[k]+",";}
        else {val +=selectedArray[k]; }
    }
    var url = "http://www.parkerriver.com/s/webforms?objtype="+
              encodeURIComponent(formObjTyp)+"&val="+ encodeURIComponent(val);
    httpRequest("GET",url,true);
}
//event handler for XMLHttpRequest
function handleResponse(){
    try{
        if(request.readyState == 4){
            if(request.status == 200){
                if(formObjTyp.length > 0 && formObjTyp == "input")   {    //working with existing radio button
                    var resp =  request.responseText;
                    if (resp != null){
                        //return value is a JSON array
                        var objt = eval(resp);
                        var sel = document.createElement("select");
                        sel.setAttribute("name","countries");
                        createOptions(sel,objt);
                        var newsel = document.getElementById("newsel");
                        reset(newsel);
                        newsel.appendChild(sel);
                    }
                } else  if(formObjTyp.length > 0 && formObjTyp == "select"){
                    var resp =  request.responseText;
                    //return value is a JSON object literal
                    var func = new Function("return "+resp);
                    var objt = func();
                    var fld = document.getElementById("select_info");
                    if(fld != null){
                        fld.innerHTML = "The server <strong>"+objt.Server_info+
                                        "</strong> reports that you have chosen<br /> the following abbreviated states: <strong>"+
                                        objt.Selected_options+"</strong>";
                    }
                }
            } else {
                //request.status is 503  if the application isn't available; 500 if the application has a bug
                alert(
                        "A problem occurred with communicating between the XMLHttpRequest object and the server program.");
            }
        }//end outer if
    } catch (err)   {
        alert("It does not appear that the server is available for this application. Please"+
              " try again very soon. \nError: "+err.message);

    }
}

function createOptions(sel,_options) {
    //_options is an array of strings that represent the values of
    //a select list, as in each option of the list. sel is the select object
    if(_options == null || _options.length==0) { return;}
    var opt = null;
    for(var i = 0; i < _options.length; i++) {
        opt = document.createElement("option");
        opt.appendChild(document.createTextNode(_options[i]));
        sel.appendChild(opt);
    }
}
//remove any existing children from an Element object
function reset(elObject){
    if(elObject != null && elObject.hasChildNodes()){
        for(var i = 0; i < elObject.childNodes.length; i++){
            elObject.removeChild(elObject.firstChild);
        }
    }
}
/* Initialize a Request object that is already constructed */
function initReq(reqType,url,bool){
    try{
        /* Specify the function that will handle the HTTP response */
        request.onreadystatechange=handleResponse;
        request.open(reqType,url,bool);
        request.send(null);
    } catch (errv) {
        alert(
                "The application cannot contact the server at the moment. "+
                "Please try again in a few seconds." );
    }
}
/* Wrapper function for constructing a Request object.
 Parameters:
  reqType: The HTTP request type such as GET or POST.
  url: The URL of the server program.
  asynch: Whether to send the request asynchronously or not. */
function httpRequest(reqType,url,asynch){
    //Mozilla-based browsers
    if(window.XMLHttpRequest){
        request = new XMLHttpRequest();
    } else if (window.ActiveXObject){
        request=new ActiveXObject("Msxml2.XMLHTTP");
        if (! request){
            request=new ActiveXObject("Microsoft.XMLHTTP");
        }
     }
    //the request could still be null if neither ActiveXObject
    //initializations succeeded
    if(request){
       initReq(reqType,url,asynch);
    }  else {
        alert("Your browser does not permit the use of all "+
        "of this application's features!");}
}