有没有办法让 Electron 主进程脚本监听带有 `postMessage` function 的页面发布的消息？

Question

I want to use the standard postMessage API function in my page scripts that are loaded by an Electron renderer process.

I want to stick to Web APIs in renderer process scripts because the application is designed to run in both Electron and on the Web (in user's preferred Web browser). I don't want to tax source code readers with the likes of if(typeof electron.= "undefined")... or similar.

Is there a way to listen on messages that are generated by the postMessage function, or events dispatched by a script window, in an Electron main process script? That will allow me to maintain a graceful fallback in the renderer process script -- a posted message that isn't processed won't also generate runtime errors if not running in Electron.

So far I have been using the preload property of the webPreferences object being passed to BrowserWindow constructor to load the following preload script which sets up a "communication bridge" I am after:

(() => {
    const electron = require("electron");
    addEventListener("message", ev => {
        switch(ev.data.type) {
            case "foobar":
                electron.ipcRenderer.send("foobar", ev.data.foobar); break;
        }
    });
})();

I can then do a postMessage({ type: "foobar", foobar: { foo: 1, bar: true } }, "*") as part of any renderer process script, and it will basically result in the renderer process sending the message to the main process, with the above set up by the preload script.

Ideally, though, if possible, I'd like to avoid having to use a preload script, but like I said I don't want to use any Electron APIs in renderer process scripts at all. If I could listen to messages posted by the renderer script "window" or to events dispatched by it, directly in the main process, that would eliminate my need for the preload script. But I don't know if it is possible, and reading the documentation gives me the impression I am going in circles or that I have exhausted my alternatives.

Answer 1

Not directly, but you can preload a script on the browser window that receives that message on the renderer process and copy that with ipcRenderer.send or invoke .