Subj : ESC key in user input
To   : Nightfox
From : Digital Man
Date : Sun Feb 07 2010 12:54 pm

  Re: ESC key in user input
  By: Nightfox to All on Sat Feb 06 2010 06:02 pm

 > In writing JavaScript mods for Synchronet, I've noticed some oddness
 > related to checking for the ESC key in user input.
 >
 > I've noticed that there is no key variable defined for ESC in sbbsdefs.js,
 > so I've always defined it in my own scripts as "\x1b" (alternatively,
 > defining the ESC key using ascii(27) also seems to work).
 >
 > In one script where I use a lightbar user interface, checking for the ESC
 > key apparently caused the script to quit unexpectedly when scrolling too
 > fast through the list of items by holding down the up or down arrow keys;
 > the problem went away when I removed the check for the ESC key.  I've also
 > noticed that Synchronet JavaScript mods tend to take a second or two to
 > respond to the ESC key, although I've seen that in other doors too,
 > including older DOS doors (i.e., IceEdit).
 >
 > Is there an issue with checking for the ESC key in user input?

Yes. Terminal escape sequences (e.g. ANSI) often begin with the escape (ASCII
27) character, for example <ESC>[2J to clear the screen.

 > Are the
 > issues that I've mentioned common, and are there any ways to get around
 > them (besides not checking for ESC)?

You'd have use a timeout mechanism, which explains the delay you see in some
scripts/programs that support ESC as a command.

                                            digital man

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