$.getJSONP

jsonp

    // fn to handle jsonp with timeouts and errors
    // hat tip to Ricardo Tomasi for the timeout logic
    $.getJSONP = function(s) {
        s.dataType = 'jsonp';
        $.ajax(s);

        // figure out what the callback fn is
        var $script = $(document.getElementsByTagName('head')[0].firstChild);
        var url = $script.attr('src') || '';
        var cb = (url.match(/callback=(\w+)/)||[])[1];
        if (!cb)
            return; // bail
        var t = 0, cbFn = window[cb];

        $script[0].onerror = function(e) {
            $script.remove();
            handleError(s, {}, "error", e);
            clearTimeout(t);
        };

        if (!s.timeout)
            return;

        window[cb] = function(json) {
            clearTimeout(t);
            cbFn(json);
            cbFn = null;
        };

        t = setTimeout(function() {
            $script.remove();
            handleError(s, {}, "timeout");
            if (cbFn)
                window[cb] = function(){};
        }, s.timeout);
        
        function handleError(s, o, msg, e) {
            // support jquery versions before and after 1.4.3
            ($.ajax.handleError || $.handleError)(s, o, msg, e);
        }
    };

http://stackoverflow.com/questions/8627201/ajax-upload-plugin-throwing-jquery-handleerror-not-found

Above version 1.5 of jQuery, the function $.handleError is undefined. Defining this function solves the problem (solved for me). I'm not aware of a better solution to jsonp.

$.handleError = function(s, xhr, status, e) {
    // If a local callback was specified, fire it
    if ( s.error ) {
        s.error.call( s.context || window, xhr, status, e );
    }

    // Fire the global callback
    if ( s.global ) {
        (s.context ? jQuery(s.context) : jQuery.event).trigger( "ajaxError", [xhr, s, e] );
    }
};

Since my solution must be compatible with IE8, this is a good work-around. But, if you can use $.get, do so.

I'm getting an error because the callback name is not set on the URL, it is still "?". The original getJSON function changes that to a random name. I'm using jquery 1.11.0

XMLHttpRequest cannot load http://localhost:8090/ehr/rest/ehrForSubject?subjectUid=&format=json&callback=?. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access. The response had HTTP status code 400.