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I am trying to write an Electron program in which the main process creates an invisible window, sends a number to that window, the window computes the factorial and then sends it back.
This is in the main process:
function invisibleWindow() {
const invisPath = 'file://' + path.join(__dirname, 'files/html/inv.html')
let win = new BrowserWindow({ width: 400, height: 400, show: false })
win.loadURL(invisPath)
win.webContents.on('did-finish-load', function () {
const input = 100;
win.webContents.send('compute-factorial', input);
})
ipcMain.on('factorial-computed', function (event, input, output) {
const message = `The factorial of ${input} is ${output}`
console.log(message);
})
}
The function gets called in the main process by:
app.on('ready', () => {
// creates different window here
invisibleWindow();
});
This is the inv.html file:
<html>
<script type="text/javascript">
const ipc = require('electron').ipcRenderer
const BrowserWindow = require('electron').remote.BrowserWindow
ipc.on('compute-factorial', function (event, number) {
const result = factorial(number)
ipcRenderer.send('factorial-computed', number, result)
window.close()
})
function factorial (num) {
if (num === 0) return 1
return num * factorial(num - 1)
}
</script>
</html>
Now after I have added this to my program, every time when I start it through the terminal, it does not terminate by itself even when all other (visible) windows are closed. I guess this is because the invisible window is still opened because it did not receive the compute-factorial event.
What am I doing wrong?
320
This is because of an race condition.
Electron docs:
Event: 'did-finish-load'
Emitted when the navigation is done, i.e. the spinner of the tab has stopped spinning, and the onload event was dispatched.
You can try it with setTimeout:
win.webContents.on('did-finish-load', function () {
setTimeout(() => {
const input = 100;
win.webContents.send('compute-factorial', input);
}, 3000);
});
The main process does not know when the DOM is ready. You can do something like this.
Send your main process an "dom-is-ready" event.
inv.html
ipc.send('dom-is-ready');
Paste your 'did-finish-load' code into 'dom-is-ready'.
main.js
function invisibleWindow() {
const invisPath = 'file://' + path.join(__dirname, 'files/html/inv.html');
const win = new BrowserWindow({
width: 400,
height: 400,
show: false
});
win.loadURL(invisPath);
win.webContents.on('did-finish-load', function () {
win.show();
});
ipcMain.on('dom-is-ready', function (event) {
const input = 100;
win.webContents.send('compute-factorial', input);
});
ipcMain.on('factorial-computed', function (event, input, output) {
const message = `The factorial of ${input} is ${output}`
console.log(message);
});
}
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