why is javascript-function just executed if an alert() is put at the beginning?

var callback = function(result){
             //alert(result);
             var json = eval('('+result+')');
             if(json.criticalerror==true) dialogCriticalError(json.errormessage);
                else{
                    if(json.error==true) dialogError(json.errormessage);
                    else{
                        // Do 开发者_运维百科something else
                    }
                }
         };

When this callback-function is executed the "Do something else" part is called without problems. But in the case the json.error is true the dialogError-function is not executed. I've checked the transmitted JSON in Firebug. Everything is ok. The result is a JSON string as it should be.

The interesting thing is, that it actually is executed if i call the JSON-response with an alert() function at the beginning of the callback function. I'm new to JavaScript and probably missing something obvious but i just can't figure it out. Where's the bug?

EDIT:

It seems the problem is the time. If i put a 100ms delay between the JSON-result and the actual callback, everything works perfectly. But this can't be right... I'm kind of clueless.

(Oh and by the way: the communication is done by JBoss Seam Remoting)

The whole function looks like that:

        function nextNode() {
         var callback = function(result){
             var json = JSON.parse(result);
             if (json.criticalerror==true) {
                    dialogCriticalError(json.errormessage);
                }else if (json.error==true) {
                    dialogError(json.errormessage);
                }else {
                        document.getElementById('currentTree').innerHTML = json.state;
                        document.getElementById('countTrees').innerHTML = json.amountSteps;
                        document.getElementById('iframe').contentWindow.importGraph(json.tree);
                        document.getElementById('relevantnode').innerHTML = json.node;
                        createNodeBar(json);
                }                
         };
        manager.nextNode(callback);
    }

The manager object is provided by the Seam Framework through the following function:

var manager = Seam.Component.getInstance("solverTreeStructure");

LAST EDIT:

Okay now i got the definite source of the problem. Its not not the Seam Remoting but the dialogError() function and the library it uses to display the dialog.

The dialogError() function looks like that:

function dialogError(error){
        TINY.box.show({html:error,width:250,height:100,close:true,mask:true,opacity:20,topsplit:3})
    }

It uses a small dialog library called TINYBOX. Now this library offers a variety of parameters to configure the dialog boxes. The 'mask' parameter caused all the trouble. It is resposible for darkening the background of the dialog box. If its turned on, TINYBOX needs a start-delay in order to work with the callback function. (i have NO idea why)

But for those who like riddles:

Thats the library. Its very small and clear. Unfortunately my JavaScript skills are not yet sophisticated enough to understand it. http://www.scriptiny.com/2011/03/javascript-modal-windows/

Thats the answer. Have a nice day folks! ;)

Just a general advice: do not mix blocks with and without {}. The following form is much more readable and you can pinpoint your problem quicker.

console.log(json);
if (json.criticalerror == true) {

    console.log("criticalerror");
    dialogCriticalError(json.errormessage);

} else if (json.error == true) {

    console.log("error");
    dialogError(json.errormessage);

} else {

    console.log("something else");
    // Do something else
}

It seems the problem is the time. If i put a 100ms delay between the JSON-result and the actual callback, everything works perfectly. But this can't be right... I'm kind of clueless.

Sounds like your doing asynchronous (ajax) communication. WHere is the rest of your code that asks the server for some data. Your handling the result before the server gives it to you. This explains the delay.