How to handle timer?

Hello Everybody

Here is my today's doubt: I generally launch a timer (one second cycle) but i just find out that user can simply block time just changing browser tab.

Is it normal? can i solve the problem in some way?

Here is my code:

Here is Behaviour:

You need to use system time here. Check out the Date plugin - it has Date.now expression, which is a system time in milliseconds. Save the system time on start of layout in a variable, and then you'll be able to calculate how much time has passed and update your clock on the screen.