JSON pointer has

json-pointer-has · version 1.0.0 · JSON & JSONL · free, no key needed

Return whether an RFC 6901 pointer exists as an own path.

Use when you need to: json pointer has · has json pointer · json pointer exists.

Supported

• json pointer has
• has json pointer
• json pointer exists

Not supported

• prototype has
• json patch

Behavior

• Accept only JSON values: null, boolean, finite number, string, array, and plain objects.
• Reject NaN, Infinity, -Infinity, undefined, BigInt, functions, symbols, Date, Map, Set, RegExp, boxed primitives, Buffer, and sparse holes.
• Canonicalize -0 to 0.
• Objects may have null or Object.prototype; use own enumerable string keys only.
• Treat __proto__, constructor, and toString as ordinary own keys. Never mutate Object.prototype.
• Output objects must be Object.create(null). Deep-clone all returned JSON values.
• Bound walk: max depth 32, max nodes 10000, max UTF-8 JSON bytes 250KiB of the input document string if provided as text; when json is already a value, bound the walked node count and depth.
• Same pointer grammar as json-pointer-get.
• present is true only if every token resolves through own properties or valid in-range array indexes.
• Invalid pointer syntax is invalid_input, not present false.
• Missing keys and out-of-range indexes yield present false. "-" is not present.

Input

• json (any JSON value, required)
• pointer (string, required): max length 1024

Output

• present (boolean, required)

Limits

• max json depth: 32
• max json nodes: 10000
• max pointer chars: 1024

Example

Request input:

{
  "json": {
    "a": [
      1
    ]
  },
  "pointer": "/a/0"
}

Response:

{
  "result": {
    "present": true
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "json-pointer-has",
  "version": "1.0.0",
  "input": {
    "json": {
      "a": [
        1
      ]
    },
    "pointer": "/a/0"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/json-pointer-has/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"json":{"a":[1]},"pointer":"/a/0"}'

The machine-readable contract is at /v1/tools/json-pointer-has/versions/1.0.0.

CLI

node cli.mjs run json-pointer-has 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• JSON flatten: Flatten a JSON value into a null-prototype map keyed by RFC 6901 JSON Pointers.
• JSON pointer get: Return the cloned JSON value at an RFC 6901 pointer.
• JSON pointer list: List RFC 6901 pointers to every reachable JSON node, root first.
• JSON unflatten: Reconstruct a JSON value from a map of RFC 6901 JSON Pointers to leaves.
• Array to JSONL: Serialize an array of JSON-safe values as JSON Lines text.
• JSON array anti join: Anti join two JSON arrays of objects on exact keys.