SPEC notes

[char0n]

A JSONPath implementation MUST raise an error for any query that is not well-formed and valid. The well-formedness and the validity of JSONPath queries are independent of the JSON value the query is applied to.

No further errors relating to the well-formedness and the validity of a JSONPath query can be raised during application of the query to a value. This clearly separates well-formedness/validity errors in the query from mismatches that may actually stem from flaws in the data.

However, the implementation MUST NOT silently malfunction. Specifically, if a valid JSONPath query is evaluated against a structured value whose size is too large to process the query correctly (for instance, requiring the processing of numbers that fall outside the range of exact values), the implementation MUST provide an indication of overflow.

Applying the name-selector to an object node selects a member value whose name equals the member name M or selects nothing if there is no such member value. Nothing is selected from a value that is not an object.

A negative index-selector counts from the array end backwards, obtaining an equivalent non-negative index-selector by adding the length of the array to the negative index. For example, the selector -1 selects the last, and the selector -2 selects the penultimate element of an array with at least two elements. As with non-negative indexes, it is not an error if such an element does not exist; this simply means that no element is selected.