I’m writing a WebExtension with no user interface. In its manifest, background.page references a stub .html file which simply has a tag referencing a .js file. That .js file now contains only this test code:
console.log("Hello A") ;
function printHello() {
console.log("Hello C");
}
document.addEventListener(
'DOMContentLoaded', function () {
console.log("Hello B") ;
let milliseconds = 5;
setTimeout(printHello, milliseconds);
}
) ;
Steps to Reproduce:
• Load this into a Firefox Nightly (2017-01-10) using Load Temporary Add-On.
• Click the Debug button.
• Click “OK” to the Incoming Connection security dialog.
Result: Developer Tools window opens, and in the Console tab, Hello A, Hello B, Hello C are printed, as expected.
• Click the Reload button.
Expected Result: Console should clear and the three Hellos A-C should reappear.
Actual Result: Console clears but only Hello C reappears.
If I change the milliseconds delay to 4, Hello C only appears about 80% of the time that I Reload. If I change it to 3, about 20%, and if less than 3, Hello C never appears. In other words, it needs at least 5 milliseconds of delay for even Hello C to work reliably. Otherwise, I get nothing at all in the console.
From watching this in my actual extension, which has more going on, at times I’ve seen the Hello A and Hello B appear momentarily after I click Reload. Also, I see the same behavior with browser.bookmarks.create() instead of setTimeout().
I think the problem is that all three Hellos are printing on each reload, but for some reason the console is cleared a few milliseconds after any function with a callback executes.
One more thing. If I instead load this extension into the current production release, Firefox 51.0.1, nothing ever prints to the console, even if I set milliseconds to 5000.
What is going on here, and how can I stop the clearing, or otherwise make all of my console.log() statements work?
