Feature request: Associate arbitrary, native-side app data with a JsVar about espruino HOT 2 CLOSED

Normally what we do for that kind of thing is we just allocate a String/flat String containing the info and put it as a child of the variable - you can prefix the name with \xff to hide it from JS. For example this is what we do in Graphics to add a gfx variable with data in it:

>var b = Graphics.createArrayBuffer(8,8,1)
=Graphics: {
  buffer: new ArrayBuffer(8)
 }

so 'gfx' is not visible normally, but if you look inside with 'trace'...

>trace(b)
#10329[r1,l1] Object {
  #10281[r1,l2] Name String [2 blocks] "__proto__"    #19[r4,l0] Object {
      #20[r1,l2] Name String [2 blocks] "constructor"        #17[r3,l0] NativeFunction 0x5e451 (1) {
     .....
   }
  }
  #10332[r1,l2] Name String [2 blocks] "buffer"    #10262[r1,l0] ArrayBuffer (offs 0, len 8)      #10312[r1,l0] String [1 blocks] "\0\0\0\0\0\0\0\0"
  #10268[r1,l2] Name String [1 blocks] "\xFFgfx"    #9718[r1,l0] FlatString [4 blocks] "\0\0\0\b\0\b\0\1\1\0\0\0\0\0\0\0\1 \0\0\0\0\x0F\0\0\0\0\7\0\7\0\xFF\x7F\xFF\x7F\0\x80\0\x80"
}
=undefined
> 

Sure, you could access it from JS if you really tried, but since JS is able to use peek to access any area of memory, anything is ultimately accessible from JS if you try hard enough, so I feel like this is good enough

from espruino.

Thanks for the quick response, @gfwilliams!

Ok, then as I understand it the whole system runs as a single trusted environment; apps can't really keep secrets from other apps.

In this context I agree that the method you describe is enough for hiding data that is not relevant to JS (apart from debugging, maybe). Sounds good.

Closing as feature already exists.

from espruino.