Errors and the sandbox

When a script goes wrong

fkdr reports the error, and a script that keeps failing is switched off.

• A parse error or a throw at load disables the script, prints the message with the file and line to chat, and paints its name red in the menu.
• A file named after an existing module is refused before any of its code runs. It appears in /fkdr script and in errors as broken, with the clash named; rename the file and reload.
• A throw inside a handler is printed and counted. After five, the script is switched off and says so, because a handler throwing twenty times a second floods the log, costs frames, and buries the first error, which was the only one worth reading.
• A refusal (an http call to a file:// URL, a command name somebody else owns) is printed but does not count towards that five: the API answering "no" is not a crash.
• An infinite loop is killed after 2.5 seconds by a watchdog, and lands in the script's error list like any other failure. Without it, one bad loop is a frozen client and a force-quit.
• /fkdr script errors reprints the last error for every script.
• Switching a broken script back on in the menu clears its failure count.

The sandbox

Scripts run in a safe box. They can use the API on these pages and ordinary JavaScript, and nothing else. What they cannot reach has a safe way in instead:

not allowed	use instead
opening files	storage
network connections	http
threads and running programs	schedule, scheduleTicks
the game's own code	player, world, render
fkdr's own code	the API on these pages

The built-in JavaScript objects (Array.prototype and friends) cannot be changed, so one script cannot change the language out from under another.

Read scripts before you run them

The sandbox means a script you have not read cannot quietly read your licence key or change your mods. Still, read scripts before you run them.