jsonp.js

/**
 * @author Max L Dolgov <bananafishbone@gmail.com>
 * @license MIT
 * 
 * JSONP simple utility
 * @param options
 * - **`url`** - `{string}` - request's URL
 * - **`success`** - `{function(<object>)}` - callback for response handling
 * - **`cbParamName:`** - '{string}' - will be passed to server as callback='jsonp' URL-param
 * - **`cbName:`** - '{string}' - will be used as a prefix for callbacks naming in global scope 
 *
 */

function JSONP (options) {
	var cbName = options && options.cbName || 'smjcb',
		callbackParamName = options.cbParamName || 'callback';
	if (!(cbName in JSONP)) {
		JSONP[cbName] = 0;
	}
	var script = document.createElement('script'),
		callback = '' + cbName + JSONP[cbName]++;

	function cleanup() {
		if (script && script.parentNode) { script.parentNode.removeChild(script); }
		if (callback in window) {
			try {
				delete window[callback];
			} catch (e) {
				window[callback] = undefined;  // IE8 support
			}
		}
	}

	window[callback] = function() {
		cleanup();
		if (options.success) {
			return options.success.apply(null, arguments);
		}
	};

	var appender = options.url.indexOf('?') == -1 ? '?' : '&';
	script.src = options.url + appender + callbackParamName + '=' + callback;
	script.async = true;
	script.onerror = function() {
		cleanup();
		if (options.error) { options.error.apply(null, arguments); }
	};

	(document.head || document.body).appendChild(script);
}

module.exports =  JSONP;