Is there a version of $getJSON that doesn't use a call back?

Question

I am implementing a callback for a 3rdParty javascript library and I need to return the value, but I need to get the value from the server. I need to do something like this:

3rdPartyObject.getCustomValue = function {
   return $.getJSON('myUrl');
}

getJson uses XMLHttpRequest which (I believe) has both synchronous and asynchronous behaviors, can I use the synchronouse behavior?

Answer 1

Looking at the jQuery source code, this is all $.getJSON does:

getJSON: function( url, data, callback ) {
    return jQuery.get(url, data, callback, "json");
},

And this is all $.get does:

get: function( url, data, callback, type ) {
    // shift arguments if data argument was omitted
    if ( jQuery.isFunction( data ) ) {
        callback = data;
        data = null;
    }

    return jQuery.ajax({
        type: "GET",
        url: url,
        data: data,
        success: callback,
        dataType: type
    });
},

No black magic there. Since you need to customize stuff other than the basic $.getJSON functionality, you can just use the low-level $.ajax function and pass the async option as false:

$.ajax({
    type: 'GET',
    url: 'whatever',
    dataType: 'json',
    success: function() { },
    data: {},
    async: false
});

Answer 2

You can also use the following before making your call:

$.ajaxSetup( { "async": false } );

I do not know the scope of the "async" property, I suspect that it is a global config. So consider whether you want to change this back to true after your synchronous call.

example:

3rdPartyObject.getCustomValue = function { 
    $.ajaxSetup( { "async": false } );
    var result = $.getJSON('myUrl');
    $.ajaxSetup( { "async": true } );
    return result;
}

Answer 3

var jsonObjectInstance = $.parseJSON(
    $.ajax(
        {
           url: "json_data_plz.cgi", 
           async: false, 
           dataType: 'json'
        }
    ).responseText
);