Calling and writing jquery/javascript functions

Question

I think I have not got the syntax correct for writing a javascript function and calling it to assign its return value to a variable.

My function is:

getObjName(objId){
  var objName ="";
$.ajax( {
    type : "GET",
    url : "Object",
    dataType: 'json',
    data : "objId="+objId,
    success : function(data) {
    objName = data;
    }
});
  return objName;
}

I am trying to call it and assign it to a variable with:

var objName = getObjName(objId);

However Eclipse is telling me that "the function getObjName(any) is undefined"

Matt · Accepted Answer · 2010-04-19 06:25:16Z

4

There are two things wrong here. First, you need to add function before getObjName

Secondly, you can't return a variable asynchronously. If you absolutely must do this, you can set the ajax to be synchronous, however this will block the running thread the entire time the ajax call is communicating to the server.

function getObjName(objId){
  var objName ="";
    $.ajax( {
        async: false,
        type : "GET",
        url : "Object",
        dataType: 'json',
        data : "objId="+objId,
        success : function(data) {
            objName = data;
        }
    });
  return objName;
}

answered Apr 19, 2010 at 6:25

Matt

44.1k6 gold badges105 silver badges103 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

T.J. Crowder Over a year ago

@OP: Strongly recommend avoiding synchronous requests, because as Matt says, they completely lock up the browser UI. Instead, pass a callback reference into the function and have the ajax success handler call the callback. getObjName then becomes (effectively) requestObjName and the response comes back some time later. It's a shift in your thinking, but once you've got the hang of it, it's really powerful.

Felix Kling · Accepted Answer · 2010-04-19 06:31:16Z

Have to declare functions with the function keyword:

function getObjName(objId){
   //...
}

But anyway, your code would not work. The Ajax call is done asynchronously that means, the function getObjName will return, before the Ajax call is finished and objName will be empty.

You could define your function to accept a callback, e.g. :

getObjName(objId, cb){
    $.ajax( {
        type : "GET",
        url : "Object",
        dataType: 'json',
        data : "objId="+objId,
        success : cb    // <-- call the callback on success
    });
}

and then later:

var objName;
getObjName(objId, function(data) {
    objName = data;    // <-- objName refers to the the variable defined 
                       // outside this function and gets set 
                       // after the Ajax call is finished
});

Collectives™ on Stack Overflow

Calling and writing jquery/javascript functions

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related