WebViewJavascriptBridge_JS.m

// This file contains the source for the Javascript side of the
// WebViewJavascriptBridge. It is plaintext, but converted to an NSString
// via some preprocessor tricks.
//
// Previous implementations of WebViewJavascriptBridge loaded the javascript source
// from a resource. This worked fine for app developers, but library developers who
// included the bridge into their library, awkwardly had to ask consumers of their
// library to include the resource, violating their encapsulation. By including the
// Javascript as a string resource, the encapsulation of the library is maintained.

#import "WebViewJavascriptBridge_JS.h"

NSString * WebViewJavascriptBridge_js() {
	#define __wvjb_js_func__(x) #x
	
	// BEGIN preprocessorJSCode
	static NSString * preprocessorJSCode = @__wvjb_js_func__(
;(function() {
	if (window.WebViewJavascriptBridge) {
		return;
	}

	if (!window.onerror) {
		window.onerror = function(msg, url, line) {
			console.log("WebViewJavascriptBridge: ERROR:" + msg + "@" + url + ":" + line);
		}
	}
	window.WebViewJavascriptBridge = {
        init:init,
        send:send,
		registerHandler: registerHandler,
		callHandler: callHandler,
		disableJavscriptAlertBoxSafetyTimeout: disableJavscriptAlertBoxSafetyTimeout,
		_fetchQueue: _fetchQueue,
		_handleMessageFromObjC: _handleMessageFromObjC
	};

	var messagingIframe;
	var sendMessageQueue = [];
    //接收消息队列
    var receiveMessageQueue = [];
	var messageHandlers = {};
	
	var CUSTOM_PROTOCOL_SCHEME = 'https';
	var QUEUE_HAS_MESSAGE = '__wvjb_queue_message__';
	
	var responseCallbacks = {};
	var uniqueId = 1;
	var dispatchMessagesWithTimeoutSafety = true;

	function registerHandler(handlerName, handler) {
		messageHandlers[handlerName] = handler;
	}
	
	function callHandler(handlerName, data, responseCallback) {
		if (arguments.length == 2 && typeof data == 'function') {
			responseCallback = data;
			data = null;
		}
		_doSend({ handlerName:handlerName, data:data }, responseCallback);
	}
	function disableJavscriptAlertBoxSafetyTimeout() {
		dispatchMessagesWithTimeoutSafety = false;
	}
    //    设置默认消息线程
    function init(messageHandler) {
        if (window.WebViewJavascriptBridge) {
            throw new error('WebViewJavascriptBridge.init called twice');
        }
        window.WebViewJavascriptBridge._messageHandler = messageHandler;
        var receiveMessages = receiveMessageQueue;
        receiveMessageQueue = null;
        for (var i = 0; i < receiveMessages.length; i++) {
            _handleMessageFromObjC(receiveMessages[i]);
        }
    }
    
    //    发送默认消息
    function send(message, responseCallback) {
        _doSend({data: message}, responseCallback);
    }
	
	function _doSend(message, responseCallback) {
		if (responseCallback) {
			var callbackId = 'cb_'+(uniqueId++)+'_'+new Date().getTime();
			responseCallbacks[callbackId] = responseCallback;
			message['callbackId'] = callbackId;
		}
		sendMessageQueue.push(message);
		messagingIframe.src = CUSTOM_PROTOCOL_SCHEME + '://' + QUEUE_HAS_MESSAGE;
	}

	function _fetchQueue() {
		var messageQueueString = JSON.stringify(sendMessageQueue);
		sendMessageQueue = [];
		return messageQueueString;
	}

	function _dispatchMessageFromObjC(messageJSON) {
		if (dispatchMessagesWithTimeoutSafety) {
			setTimeout(_doDispatchMessageFromObjC);
		} else {
			 _doDispatchMessageFromObjC();
		}
		
		function _doDispatchMessageFromObjC() {
			var message = JSON.parse(messageJSON);
			var messageHandler;
			var responseCallback;

			if (message.responseId) {
				responseCallback = responseCallbacks[message.responseId];
				if (!responseCallback) {
					return;
				}
				responseCallback(message.responseData);
				delete responseCallbacks[message.responseId];
			} else {
				if (message.callbackId) {
					var callbackResponseId = message.callbackId;
					responseCallback = function(responseData) {
						_doSend({ handlerName:message.handlerName, responseId:callbackResponseId, responseData:responseData });
					};
				}
				
				var handler = messageHandlers[message.handlerName];
				if (!handler) {
					console.log("WebViewJavascriptBridge: WARNING: no handler for message from ObjC:", message);
				} else {
					handler(message.data, responseCallback);
				}
			}
		}
	}
	
	function _handleMessageFromObjC(messageJSON) {
        //加入接收消息队列
        console.log(messageJSON);
        if (receiveMessageQueue) {
            receiveMessageQueue.push(messageJSON);
        }
        _dispatchMessageFromObjC(messageJSON);
	}

	messagingIframe = document.createElement('iframe');
	messagingIframe.style.display = 'none';
	messagingIframe.src = CUSTOM_PROTOCOL_SCHEME + '://' + QUEUE_HAS_MESSAGE;
	document.documentElement.appendChild(messagingIframe);

	registerHandler("_disableJavascriptAlertBoxSafetyTimeout", disableJavscriptAlertBoxSafetyTimeout);
	
	setTimeout(_callWVJBCallbacks, 0);
	function _callWVJBCallbacks() {
		var callbacks = window.WVJBCallbacks;
		delete window.WVJBCallbacks;
		for (var i=0; i<callbacks.length; i++) {
			callbacks[i](WebViewJavascriptBridge);
		}
	}
})();
	); // END preprocessorJSCode

	#undef __wvjb_js_func__
	return preprocessorJSCode;
};