fromJsPath
Creates a KPointer from a JavaScript access path string: the static member-access subset of JavaScript syntax used by APIs such as Vega-Lite's encoding.*.field (dot segments, quoted-bracket segments, and numeric-bracket segments, with backslash escaping).
Parsing rules:
An empty string returns ROOT.
Segments are separated by
.or by[...]brackets; a bracket may immediately follow a dot segment or another bracket (foo[0]['bar']).A bracket contains either a run of digits (
[0]) or a single- or double-quoted string (['a'],["a"]), whose contents become the segment verbatim;\inside a quoted bracket escapes the active quote character or a literal\.Inside a dot segment,
\escapes a literal.,[,], or\into the segment.Empty segments are rejected: a leading
., a trailing., and consecutive dots all produce one.
Return
A KPointer whose segments correspond to the parsed access path.
Parameters
The JavaScript access path string.
Throws
if path is syntactically malformed: an unterminated bracket or quote, an empty bracket, a dangling backslash, junk after a closing quote, or an empty segment.