By what means to understand how much the page is loaded?

Question

JavaScript

On some sites I see that there is a loading indicator. And not just a preloader (spinners) (without numbers, percentages, percentage of fullness), but with approximate indicators. Where percentages are displayed, etc. How it works? That is, I now understand how to get the statuses loaded and loaded, but how to get intermediate data?

Answer 1

1. Lie to the user (the easiest one)
2. Make a list of resources and load them in the loader, everything will be fine here
3. Put a spinner

Answer 2

but with approximate indicators. Where percentages are displayed, etc.

Do you happen to believe in pop-up notifications? Like this:

Ivanov I. I. from Bobruisk just bought this product

Just make a scale with percentages and the closer to 100, the slower increase the number of pseudo percentages. Upon the onset of a full load, accelerate the increase in pseudo-percentage and remove the indicator by 100.