How does js terminate the program? return cannot change jfslk_javascript skills-js tutorial

Alert (3) is such a program that is not written in the function. I wonder, how can I end JavaScript? Jfslk can achieve the same effect (end js program) alert (3)
In this case, the program is not written in the function. I wonder, how can I end JavaScript?

Alert (3)
Return;
Alert (3)
If this write fails, return can only terminate the function.

I cannot find a solution on the Internet. Ask a friend. I can say no, and I can try die.

Alert (3)
Die;
Alert (3)
Wow, I admire it. It's a success.

Alert (typeof die)
What's going on: undefined, undefined, and the console reports an error

Alert (3)
Jfslk;
Alert (3)
Ah, it turns out that this jfslk can achieve the same effect (terminating the js program)

It turns out that errors can be used to terminate js programs, which is very useful! Does anyone use this ?!