The X Command

I have added the 'X' command which will tell you the state of the

heap (-2 is ok) and how much memory is left. For me this usually
starts out around 75K-80K.

As the game progresses, more and more memory is allocated which

isn't freed, though it is no longer needed. Consequently, you
should probably do the X command once in a while, and save the
game when it starts to get really low.

Do they have such command for JavaScript?

Who is they?

JavaScript "community"
Memory allocation tools
Debugging tools
Competent programmers under 30

Laffing aut laud