是否有一种简单的转换方法,用于将chrome消息传递转换为safari消息传递语法？

Question

我的Chrome扩展程序使用邮件传递从后台页面上扩展程序内置的localstorage区域中检索各种值.

关于chrome消息传递我喜欢的事情是,它允许你在sendMessage调用中包含一个回调函数,如下所示:

chrome.runtime.sendMessage({greeting: "hello"}, function(response) {
    console.log(response.farewell);   
});

并且相应的邮件接收代码如下所示(Chrome扩展文档中的示例代码):

chrome.runtime.onMessage.addListener(
  function(request, sender, sendResponse) {
    console.log(sender.tab ?
                "from a content script:" + sender.tab.url :
                "from the extension");
    if (request.greeting == "hello")
      sendResponse({farewell: "goodbye"});
  });

我正在尝试将我的扩展转换为Safari扩展格式,但我无法弄清楚如何将Chrome sendMessage/onMessage函数映射到Safari的 safari.self.tab.dispatchMessage(name, data)消息处理函数

甚至可以在Safari的dispatchMessage函数调用中包含回调函数吗？如果没有,我应该如何解决这个限制？

Answer 1

在仅提供单向消息传递系统的环境中,您始终可以自己实现"带回调消息",方法是将唯一ID与每条消息相关联,并将回调存储在将这些ID映射到回调的字典中.

在这个答案的最后,我从我的跨浏览器Lyrics Here扩展的源代码中复制粘贴了Safari特定的存储模块,该扩展提供了以下API:

• config.getItem(key, callback)
• config.setItem(key, value, callback)
• config.removeItem(key, callback)
• config.clear(callback)

回调getItem包含与密钥关联的值(如果找到).其他回调接收一个布尔值,告诉操作是否成功.

源代码已注释,并包含处理一些边缘情况的片段.如果有什么不清楚的话,请随意向我提出几个问题.

config-safari.js(AMD)

// Adapter for maintaining preferences (Safari 5+)
// All methods are ASYNCHRONOUS
define('config-safari', function() {
    var config = {};
    var callbacks = {};
    ['getItem', 'setItem', 'removeItem', 'clear'].forEach(function(methodName) {
        config[methodName] = function() {
            var args = [].slice.call(arguments);
            var callback = args.pop();
            var messageID = Math.random();
            callbacks[messageID] = callback;

            var message = {
                type: methodName,
                messageID: messageID,
                args: args
            };
            safari.self.tab.dispatchMessage('config-request', message);
        };
    });
    config.init = function() {
        if (typeof safari === 'undefined') {
            // Safari bug: safari is undefined when current context is an iframe
            // and src="javascript:''"
            // This error is only expected on YouTube.
            // config.getItem is triggered in main, so we just redefine
            // it. Don't overwrite setItem, etc., so that errors are thrown
            // when these methods are used.
            config.getItem = function(key, callback){
                callback();
            };
            return;
        }
        safari.self.addEventListener('message', function(event) {
            if (event.name === 'config-reply') {
                var messageID = event.message.messageID;
                var callback = callbacks[messageID];
                // Check if callback exists. It may not exist when the script is
                // activated in multiple frames, because every frame receives the message
                if (callback) {
                    delete callbacks[messageID];
                    callback(event.message.result);
                }
            }
        }, true);
    };
    return config;
});

global.html的片段:

<script>
(function(exports) {
    var config = {};
    config.getItem = function(key, callback) {
        var result = safari.extension.settings.getItem(key);
        if (typeof result === 'string') {
            try {
                result = JSON.parse(result);
            } catch (e) {
                // Extremely unlikely to happen, but don't neglect the possibility
                console.log('config.getItem error: ' + e);
                result = undefined;
            }
        }
        callback(result);
    };
    // callback's argument: true on success, false otherwise
    config.setItem = function(key, value, callback) {
        var success = false;
        try {
            value = JSON.stringify(value);
            // Safari (5.1.5) does not enforce the database quota,
            // let's enforce it manually (ok, set the quota per key, since
            // the performance issue only occur when a specific key has an outrageous high value)
            // 1 MB should be sufficient.
            if (value.length > 1e6) {
                throw new Error('QUOTA_EXCEEDED_ERR: length=' + value.length);
            }
            safari.extension.settings.setItem(key, value);
            success = true;
        } catch (e) {
            console.log('config.setItem error: ' + e);
        }
        callback(success);
    };
    // callback's argument: true on success, false otherwise
    config.removeItem = function(key, callback) {
        safari.extension.settings.removeItem(key);
        callback(true);
    };
    // callback's argument: true on success, false otherwise
    config.clear = function(callback) {
        safari.extension.settings.clear();
        callback(true);
    };

    // config's message handler
    function handleConfigRequest(event) {
        var args = event.message.args;
        // Last argument: Always a callback
        args.push(function(result) {
            // Note: All of the config methods send a callback only once
            // Behavior for calling the callback twice is undefined.

            // Send a reply to trigger the callback at the sender's end
            event.target.page.dispatchMessage('config-reply', {
                messageID: event.message.messageID,
                result: result
            });
        });
        config[event.message.type].apply(config, args);
    }

    // Export
    exports.handleConfigRequest = handleConfigRequest;
})(window);
</script>
<script>
safari.application.addEventListener('message', function(event) {
    switch (event.name) {
        case 'config-request':
            handleConfigRequest(event);
            break;
        /* ... other things removed ... */
    }
}, true);
</script>