zdpjs_webrtc/api/labs/easyrtc_sc_extension/content-script.js

基于easyrtc二次开发的webrtc框架

/* global chrome */

// this content-script plays role of medium to publish/subscribe messages from webpage to the background script

// this object is used to make sure our extension isn't conflicted with irrelevant messages!
var rtcmulticonnectionMessages = {
    'is-extension-loaded': true,
    'get-sourceId':  true
};

// this port connects with background script
var port = chrome.runtime.connect();

// if background script sent a message
port.onMessage.addListener(function (message) {
    // get message from background script and forward to the webpage
    window.postMessage(message, '*');
});

// this event handler watches for messages sent from the webpage
// it receives those messages and forwards to background script
window.addEventListener('message', function (event) {

    // if invalid source
    if (event.source !== window) {
        return;
    }
        
    // it is 3rd party message
    if (!rtcmulticonnectionMessages[event.data]) {
        return;
    }
        
    // if browser is asking whether extension is available
    if (event.data === 'is-extension-loaded') {
        return window.postMessage('extension-loaded', '*');
    }

    // if it is something that need to be shared with background script
    if (event.data === 'get-sourceId') {
        // forward message to background script
        port.postMessage(event.data);
    }
});

// inform browser that you're available!
window.postMessage('extension-loaded', '*');