Semantics changes are the same as at 548ef078 .
Also, the previous C implementation returnd a string for the `stdout`
value, but stdout of the subprocess command is MPV_FORMAT_BYTE_ARRAY
which js previously didn't support, so support it too (at pushnode)
by returning it as a string - the same as the lua code does.
When dump's argument is an array, it was displaying <VISITED> for all
the array's object elements (objects, arrays, etc), regardless if they're
actually visited or not.
The reason is that we try to stringify twice: once normally which may
throw (on cycles), and a second time while excluding visited items which
is indicated by binding the replacer to an empty array - in which we hold
the visited items, where the replacer tests if its 'this' is an array or
not and acts accordingly.
However, its "this" may also be an array even if we don't bind it to one,
because its "normal" this is the main stringified object, so the test of
Array.isArray(this) is true when the top object is an array, and the object
items are indeed are in it - so the replacer considers them visited.
Fix by binding to null on the first attempt such that "this" is an array
only when we want it to test for visited items and not when the argument
itself is an array.
Due to earlier misinterpretation of the Lua docs as if mp.register_idle
registers a one-shot callback, the JS docs suggested to use setTimeout.
But the behavior and Lua docs are such that it's a repeating callback
which fires just before the script thread goes to sleep.
Implement it for JS too.
Implements JS with almost identical API to the Lua support.
Key differences from Lua:
- The global mp, mp.msg and mp.utils are always available.
- Instead of returning x, error, return x and expose mp.last_error().
- Timers are JS standard set/clear Timeout/Interval.
- Supports CommonJS modules/require.
- Added at mp.utils: getenv, read_file, write_file and few more.
- Global print and dump (expand objects) functions.
- mp.options currently not supported.
See DOCS/man/javascript.rst for more details.
