Question

I can get the mapUrl use function fecthData.
but it cannot show the map.
and if i um-commented the alert line code, it will show the map.
Anyone can give me some tips?
Thanks in advance.

dojo.require("esri.map");
var mapLayer;
var mapUrl;
function init() {
   // use ajax to get map url
   fecthData("MapInfo?id=1", function (d) {mapUrl = d.mapUrl;});

   map = new esri.Map("map");
   // if um-commented below line, the map will show
   //alert("mapUrl"+mapUrl);

   // map layer
   mapLayer = new esri.layers.ArcGISDynamicMapServiceLayer(mapUrl);
   if ( mapLayer == undefined )
       return;
   dojo.connect(mapLayer, "onLoad", initFunc);
   map.addLayer(mapLayer);
}
function fecthData(varUrl, varFunc) {
   var options = {
    type: "POST",
    url: varUrl,
    data: "",
    contentType: "application/json;charset=utf-8",
    dataType: "json",
    cache: false,
    success: varFunc
 };
  //execute the ajax call and get a response
  var request = $.ajax(options);
}
dojo.addOnLoad(init);

Answer 1

Looks like your “fecthData” gets the response AFTER your “init” execution ends. I guess that you should init your map right after your “fecthData” is completed, like this:

dojo.require("esri.map");
var map, mapUrl, mapLayer;

function init() {
   fecthData("MapInfo?id=1");
}
function fecthData(varUrl) {
   var options = {
    type: "POST",
    url: varUrl,
    data: "",
    contentType: "application/json;charset=utf-8",
    dataType: "json",
    cache: false,
    success: function (d) {
        mapUrl = d.mapUrl;
        if ( mapUrl == undefined )
            return;
        map = new esri.Map("map");
        mapLayer = new esri.layers.ArcGISDynamicMapServiceLayer(mapUrl);
        dojo.connect(map, "onLoad", someFunction); // layer object doesn't have any onLoad event, so I changed it
        map.addLayer(mapLayer);
    }
 };
 var request = $.ajax(options);
}
dojo.addOnLoad(init);

or something like that