JSONP.coffee

JSONP = do (win = window, doc = document) ->
  head = doc.getElementsByTagName('head')[0]

  createScript = (url) ->
    node = doc.createElement('script')
    node.onload = -> head.removeChild node
    node.onerror = ->
      head.removeChild node
      throw new Error 'JSONP load script error'
    node.src = url
    head.appendChild node

  genCallbackName = do ->
    expando = 'CB'+(''+Math.random()).replace( /\D/g, "")
    callbackId = 0
    -> [expando, callbackId++].join('_')

  genGlobalCallback = (callbackName, fn) ->
    win[callbackName] = ->
      try
        fn arguments...
      catch error
        throw new Error 'JSONP genGlobalCallback can not apply function'
      delete win[callbackName]

  (url, fn, paramName = 'callback') ->
    cbName = genCallbackName()
    symbol = if /\?/.test(url) then '&' else '?'
    cbUrl = [url, symbol, paramName, '=', cbName].join('')
    cb = genGlobalCallback cbName, fn
    createScript(cbUrl, cb)


#log = console.log.bind('JSONP: ')  # can not apply bind function
log = ->
  console.count 'done'
  console.log 'done', arguments...

# TestCase
JSONP('http://ip.jsontest.com/', log)
JSONP('http://ip.jsontest.com/?mime=5', log)

JSONP.js

// Generated by CoffeeScript 1.9.3
(function() {
  var JSONP, log;
  var slice = [].slice;
  JSONP = (function(win, doc) {
    var createScript, genCallbackName, genGlobalCallback, head;
    head = doc.getElementsByTagName('head')[0];
    createScript = function(url) {
      var node;
      node = doc.createElement('script');
      node.onload = function() {
        return head.removeChild(node);
      };
      node.onerror = function() {
        head.removeChild(node);
        throw new Error('JSONP load script error');
      };
      node.src = url;
      return head.appendChild(node);
    };
    genCallbackName = (function() {
      var callbackId, expando;
      expando = 'CB' + ('' + Math.random()).replace(/\D/g, "");
      callbackId = 0;
      return function() {
        return [expando, callbackId++].join('_');
      };
    })();
    genGlobalCallback = function(callbackName, fn) {
      return win[callbackName] = function() {
        var error;
        try {
          fn.apply(null, arguments);
        } catch (_error) {
          error = _error;
          throw new Error('JSONP genGlobalCallback can not apply function');
        }
        return delete win[callbackName];
      };
    };
    return function(url, fn, paramName) {
      var cb, cbName, cbUrl, symbol;
      if (paramName == null) {
        paramName = 'callback';
      }
      cbName = genCallbackName();
      symbol = /\?/.test(url) ? '&' : '?';
      cbUrl = [url, symbol, paramName, '=', cbName].join('');
      cb = genGlobalCallback(cbName, fn);
      return createScript(cbUrl, cb);
    };
  })(window, document);
  log = function() {
    console.count('done');
    return console.log.apply(console, ['done'].concat(slice.call(arguments)));
  };
  JSONP('http://ip.jsontest.com/', log);
  return JSONP('http://ip.jsontest.com/?mime=5', log);
})();