jsonp.js

var reqs = [];

window.jsonp_handler = function(id, res) {
    reqs[id].handle(res);
};

function Req(url, data, handler) {
    this.url = url;
    this.data = typeof data == "object" ? data : {};
    this.handler = handler;
    this.id = Math.ceil(Math.random() * 10000).toString();
    this.timeoutTimer = setTimeout(this.onTimeout.bind(this), 2000);

    var args = "";
    for (var k in this.data) {
        var v = this.data[k];

        args += "&" + encodeURIComponent(k) + "=" + encodeURIComponent(v);
    }

    this.script = document.createElement("script");
    this.script.type = "text/javascript";
    this.script.src = this.url + "?p=" + this.id + args;
    document.body.appendChild(this.script);

    reqs[this.id] = this;
}

Req.prototype.onTimeout = function() {
    this.delete();
};

Req.prototype.delete = function() {
    delete reqs[this.id];
    clearTimeout(this.timeoutTimer);
    this.script.remove();
};

Req.prototype.handle = function(res) {
    this.delete();

    var data;
    if (this.handler && (data = this.handler(res))) {
        new Req(this.url, data, this.handler);
    }
};

module.exports = function(url, data, handler) {
    return new Req(url, data, handler);
}