Using ipc in Electron to set global variable from renderer

Question

renderer.js

ipcRenderer.sendSync('setGlobal', 'globalVarName').varInner.varInner2 = 'result';

main.js

global.globalVarName = {
  varInner: {
    varInner2: ''
  },
  iWontChange: 'hi'
};

ipcMain.on('setGlobal', (event, arg) => {
  console.log(arg) // should print "result"
  // what goes here?
})

console.log(varInner2) // should print "result"

Is something like this possible, namely setting the varInner2 of globalVarName in this manner? Secondly, is there a way to optimize this so we wouldn't have to rewrite this process for every global variable (i.e. some way to do this with dynamic variable names)?

I appreciate any ideas or solutions, sorry if this is a common sense question.

Answer 1

Use IPC to Set the Global's Value.

Using getGlobal works great when you're only interested in reading the value of the global variable. However, I found that trying to assign or change its value using getGlobal to be problematic.

In my case, I found that the global variable on the Main process didn't actual change. Specifically, when refreshing the Electron window in development, the global variables were set back to their original value. This made restoring state in development an issue.

Not sure if this also was occurring in production, but I imagine it would, so spinning up new processes that relied on up-to-date values of global variables would be problematic.

Instead, I ended up using the more verbose method of ipcMain and ipcRenderer.

main.js

const { ipcMain } = require( "electron" );

ipcMain.on( "setMyGlobalVariable", ( event, myGlobalVariableValue ) => {
  global.myGlobalVariable = myGlobalVariableValue;
} );

renderer.js

const { ipcRenderer, remote } = require( "electron" );

// Set MyGlobalVariable.
ipcRenderer.send( "setMyGlobalVariable", "Hi There!" );

// Read MyGlobalVariable.
remote.getGlobal( "MyGlobalVariable" ); // => "Hi There!"