jsonp_client.js

function jsonPClient(urlTarget, success, error) {
    successSafe = success || function(){};
    errorSafe = error || function(){};

    var hash = Math.random().toString()
        .replace('0.', '');
    var callbackName = 'jsonp_client_' + hash;

    window[callbackName] = function(data){
        cleanUp();
        successSafe(data);
    }

    var scriptTarget = document.createElement('script');
    scriptTarget.type = 'text/javascript';
    scriptTarget.async = true;
    //scriptTarget.charset = ...

    var stamp = new Date().valueOf();
    var src = urlTarget + '?callback=' + callbackName + '&stamp=' + stamp;
    scriptTarget.src = src;

    scriptTarget.onerror = function(a, b, c){
        cleanUp();
        errorSafe(a, b, c);
    };

    var scriptHost = getScriptHost();
    scriptHost.insertBefore(scriptTarget, scriptHost.firstChild );

    function cleanUp(){
        delete window[callbackName];

        scriptHost.removeChild(scriptTarget);
        scriptHost = null;
        scriptTarget.onerror = null;
        scriptTarget = null;
    }
    function getScriptHost(){
        var scriptHost = document.head || document.getElementsByTagName("head")[0] || document.documentElement;
        return scriptHost;
    };
};