[Bug]: Performance issues with contextBridge

[iptop]

Preflight Checklist

• I have read the Contributing Guidelines for this project.
• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for a bug report that matches the one I want to file, without success.

Electron Version

25.9.8

What operating system are you using?

Windows

Operating System Version

Windows 11 23H2

What arch are you using?

x64

Last Known Working Electron version

No response

Expected Behavior

Because function calls through contextBridge actually involve parameter passing by copying, this leads to poor performance in scenarios with large amounts of data.

preload.js

const { contextBridge, ipcRenderer } = require('electron')
let arr = new ArrayBuffer(1080 * 1920 * 4)
function testFunc (cb) {
  cb(arr)
}

contextBridge.exposeInMainWorld('electron', {
  testFunc
})

WEB.js

let s = (new Date()).getTime()
window.electron.testFunc(()=>{
  let e = (new Date()).getTime()
  console.log(e-s) // 10ms
})

Actual Behavior

I hope there is a way, like postMessage, to transfer control and avoid a large amount of data copying.

Testcase Gist URL

No response

Additional Information

No response

[Prinzhorn]

First search result I found #27024

So you can use postMessage between renderer and the preload script.

The main reason to use contextBridge is for synchronous messaging between the isolated world and main world. If you don't need synchronous messaging, window.postMessage works just as well.

#27024 (comment)

[iptop]

@Prinzhorn Your response successfully solved my problem.However, I have a question. Since it's supposed to be context isolated, why can the preload.js file access the same window object as the rendering process？

[Prinzhorn]

Read the linked issue:

#27024 (comment)