// .. recursive descent. JSONPath borrows this syntax from E4X.
* wildcard. All objects/elements regardless their names.
[] [] subscript operator. XPath uses it to iterate over element collections and for predicates. In Javascript and JSON it is the native array operator.
| [,] Union operator in XPath results in a combination of node sets. JSONPath allows alternate names or array indices as a set.
n/a [start🔚step] array slice operator borrowed from ES4.
[] ?() applies a filter (script) expression.
unsupported syntax:
n/a () script expression, using the underlying script engine.
filter script expression only supports finit expression like:
@aaa op other
@.number >= $.number // means filters the current node which number greater than root number