docs: add JSON Pointer quick start

docs/docs/intro.mdx

@@ -5,11 +5,11 @@ import TabItem from "@theme/TabItem";
 
 JSON P3 implements JSONPath following the [IETF JSONPath draft](https://datatracker.ietf.org/doc/html/draft-ietf-jsonpath-base-20) specification, JSON Pointer described by [RFC 6901](https://datatracker.ietf.org/doc/html/rfc6901), and JSON Patch described by [RFC 6902](https://datatracker.ietf.org/doc/html/rfc6902).
 
-JSONPath is a mini language for selecting values from JSON-like data. A JSONPath query has the potential to return multiple values from a data structure, along with their locations. This implementation is non-evaluating and read-only. We strictly follow the [IETF JSONPath draft](https://datatracker.ietf.org/doc/html/draft-ietf-jsonpath-base-20).
+**JSONPath** is a mini language for selecting values from JSON-like data. A JSONPath query has the potential to return multiple values from a data structure, along with their locations. This implementation is non-evaluating and read-only. We strictly follow the [IETF JSONPath draft](https://datatracker.ietf.org/doc/html/draft-ietf-jsonpath-base-20).
 
-JSON Pointer is a syntax for targeting a single value in JSON-like data. JSON Pointers can be _resolved_ against data to retrieve the value, or used as part of a JSON Patch operation.
+**JSON Pointer** is a syntax for targeting a single value in JSON-like data. JSON Pointers can be _resolved_ against data to retrieve the value, or used as part of a JSON Patch operation.
 
-JSON Patch is a standard for describing update operations to perform on JSON-like data. You can _apply_ a patch to _add_, _remove_, _replace_, _move_, _copy_ and _move_ values within a JSON document.
+**JSON Patch** is a standard for describing update operations to perform on JSON-like data. You can _apply_ a patch to _add_, _remove_, _replace_, _copy_ and _move_ values within a JSON document.
 
 We use the term _JSON-like data_ to describe arbitrary, possibly nested, JavaScript arrays and objects, plus primitive strings, numbers, booleans and `null`, as you might expect from `JSON.parse()`. When traversing JSON-like data, we only resolve an object's direct properties, and the `length` property of arrays and strings is ignored.
 

docs/docs/quick-start.md

@@ -122,15 +122,78 @@ console.log(nodes.values()); // [ 'John', 'Sally', 'Jane' ]
 
 ## JSON Pointer
 
-TODO:
+Resolve a JSON Pointer ([RFC 6901](https://datatracker.ietf.org/doc/html/rfc6901)) against some data using `jsonpointer.resolve()`.
+
+```javascript
+import { jsonpointer } from "json-p3";
+
+const data = {
+  users: [
+    { name: "Sue", score: 100 },
+    { name: "John", score: 86 },
+    { name: "Sally", score: 84 },
+    { name: "Jane", score: 55 },
+  ],
+};
+
+const rv = jsonpointer.resolve("/users/1", data);
+console.log(rv); // { name: 'John', score: 86 }
+```
+
+`resolve()` is a convenience function equivalent to `new JSONPointer(pointer).resolve(data)`. Use the [`JSONPointer`](./api/classes/jsonpointer.JSONPointer.md) constructor when you need to resolve the same pointer repeatedly against different data.
+
+```javascript
+import { JSONPointer } from "json-p3";
+
+const someData = {
+  users: [
+    { name: "Sue", score: 100 },
+    { name: "John", score: 86 },
+    { name: "Sally", score: 84 },
+  ],
+};
+
+const otherData = {
+  users: [{ name: "Brian" }, { name: "Roy" }],
+};
+
+const pointer = new JSONPointer("/users/1");
+console.log(pointer.resolve(someData)); // { name: 'John', score: 86 }
+console.log(pointer.resolve(otherData)); // { name: 'Roy' }
+```
 
 ### Errors and fallbacks
 
-TODO:
+If the pointer can't be resolved against the argument JSON value, one of [`JSONPointerIndexError`](./api/classes/jsonpointer.JSONPointerIndexError.md), [`JSONPointerKeyError`](./api/classes/jsonpointer.JSONPointerKeyError.md) or [`JSONPointerTypeError`](./api/classes/jsonpointer.JSONPointerTypeError.md) is thrown. All three exceptions inherit from [`JSONPointerResolutionError`](./api/classes/jsonpointer.JSONPointerResolutionError.md).
+
+```javascript
+// .. continued from above
+const rv = pointer.resolve("/users/1/age", data);
+// JSONPointerKeyError: no such property ("/users/1/age")
+```
+
+A fallback value can be given as a third argument, which will be returned in the event of a `JSONPointerResolutionError`.
+
+```javascript
+// .. continued from above
+const rv = pointer.resolve("/users/1/age", data, -1);
+console.log(rv); // -1
+```
 
 ### Relative JSON Pointers
 
-TODO:
+We support [Relative JSON Pointers](https://www.ietf.org/id/draft-hha-relative-json-pointer-00.html) via the [`to(rel)`](./api/classes/jsonpointer.JSONPointer.md#to) method of `JSONPointer`, where `rel` is a relative JSON pointer string, and a new `JSONPointer` is returned.
+
+```javascript
+import { JSONPointer } from "json-p3";
+
+const data = { foo: { bar: [1, 2, 3], baz: [4, 5, 6] } };
+const pointer = new JSONPointer("/foo/bar/2");
+
+console.log(pointer.resolve(data)); // 3
+console.log(pointer.to("0-1").resolve(data)); // 2
+console.log(pointer.to("2/baz/2").resolve(data)); // 6
+```
 
 ## JSON Patch
 

src/path/environment.ts

@@ -128,6 +128,8 @@ export class JSONPathEnvironment {
     return this.compile(path).query(value);
   }
 
+  // TODO: match(path, value): boolean
+
   protected setupFilterFunctions(): void {
     this.functionRegister.set("count", new CountFilterFunction());
     this.functionRegister.set("length", new LengthFilterFunction());

src/pointer/errors.ts

@@ -9,6 +9,9 @@ export class JSONPointerError extends Error {
   }
 }
 
+/**
+ * Base class for JSON Pointer resolution errors.
+ */
 export class JSONPointerResolutionError extends JSONPointerError {
   constructor(readonly message: string) {
     super(message);
@@ -17,6 +20,9 @@ export class JSONPointerResolutionError extends JSONPointerError {
   }
 }
 
+/**
+ * Error thrown due to an out of range index when resolving a JSON Pointer.
+ */
 export class JSONPointerIndexError extends JSONPointerResolutionError {
   constructor(readonly message: string) {
     super(message);
@@ -25,6 +31,9 @@ export class JSONPointerIndexError extends JSONPointerResolutionError {
   }
 }
 
+/**
+ * Error thrown due to a missing property when resolving a JSON Pointer.
+ */
 export class JSONPointerKeyError extends JSONPointerResolutionError {
   constructor(readonly message: string) {
     super(message);
@@ -33,6 +42,9 @@ export class JSONPointerKeyError extends JSONPointerResolutionError {
   }
 }
 
+/**
+ * Error thrown due to invalid JSON Pointer syntax.
+ */
 export class JSONPointerSyntaxError extends JSONPointerError {
   constructor(readonly message: string) {
     super(message);
@@ -41,6 +53,9 @@ export class JSONPointerSyntaxError extends JSONPointerError {
   }
 }
 
+/**
+ * Error thrown when trying to resolve a property or index against a primitive value.
+ */
 export class JSONPointerTypeError extends JSONPointerResolutionError {
   constructor(readonly message: string) {
     super(message);