Fix move and copy to end of array with JSON Patch

Author: jg-rp

CHANGELOG.md

@@ -1,5 +1,11 @@
 # JSON P3 Change Log
 
+## Version 1.3.5 (unreleased)
+
+**Fixes**
+
+- Fixed a JSON Patch bug where we would not allow moving or copying to the end of an array using the special JSON Pointer token `-`.
+
 ## Version 1.3.4
 
 **Fixes**

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "json-p3",
-  "version": "1.3.4",
+  "version": "1.3.5",
   "author": "James Prior",
   "license": "MIT",
   "description": "JSONPath, JSON Pointer and JSON Patch",
@@ -37,43 +37,43 @@
     "dist/**/*"
   ],
   "devDependencies": {
-    "@babel/cli": "^7.23.4",
-    "@babel/core": "^7.23.7",
-    "@babel/preset-env": "^7.23.7",
-    "@babel/preset-typescript": "^7.23.3",
+    "@babel/cli": "^7.25.9",
+    "@babel/core": "^7.26.0",
+    "@babel/preset-env": "^7.26.0",
+    "@babel/preset-typescript": "^7.26.0",
     "@jest/globals": "^29.7.0",
     "@rollup/plugin-babel": "^6.0.4",
-    "@rollup/plugin-commonjs": "^25.0.7",
-    "@rollup/plugin-node-resolve": "^15.2.3",
-    "@rollup/plugin-replace": "^5.0.5",
+    "@rollup/plugin-commonjs": "^25.0.8",
+    "@rollup/plugin-node-resolve": "^15.3.0",
+    "@rollup/plugin-replace": "^5.0.7",
     "@rollup/plugin-terser": "^0.4.4",
-    "@rollup/plugin-typescript": "^11.1.5",
-    "@types/jest": "^29.5.11",
-    "@typescript-eslint/eslint-plugin": "^6.17.0",
-    "@typescript-eslint/parser": "^6.17.0",
-    "eslint": "^8.56.0",
+    "@rollup/plugin-typescript": "^11.1.6",
+    "@types/jest": "^29.5.14",
+    "@typescript-eslint/eslint-plugin": "^8.17.0",
+    "@typescript-eslint/parser": "^8.17.0",
+    "eslint": "^8.57.1",
     "eslint-config-prettier": "^9.1.0",
-    "eslint-plugin-escompat": "^3.4.0",
+    "eslint-plugin-escompat": "^3.11.4",
     "eslint-plugin-eslint-comments": "^3.2.0",
     "eslint-plugin-filenames": "^1.3.2",
-    "eslint-plugin-github": "^4.10.1",
+    "eslint-plugin-github": "^4.10.2",
     "eslint-plugin-i18n-text": "^1.0.1",
-    "eslint-plugin-import": "^2.29.1",
+    "eslint-plugin-import": "^2.31.0",
     "eslint-plugin-jsdoc": "^47.0.2",
-    "eslint-plugin-n": "^16.6.1",
-    "eslint-plugin-no-only-tests": "^3.1.0",
+    "eslint-plugin-n": "^16.6.2",
+    "eslint-plugin-no-only-tests": "^3.3.0",
     "eslint-plugin-node": "^11.1.0",
-    "eslint-plugin-prettier": "^5.1.2",
-    "eslint-plugin-promise": "^6.1.1",
+    "eslint-plugin-prettier": "^5.2.1",
+    "eslint-plugin-promise": "^6.6.0",
     "eslint-plugin-sonarjs": "^0.23.0",
     "eslint-plugin-tsdoc": "^0.2.17",
     "iregexp-check": "^0.1.1",
     "jest": "^29.7.0",
-    "prettier": "^3.1.1",
-    "rollup": "^4.9.2",
-    "ts-jest": "^29.1.1",
-    "tslib": "^2.6.2",
-    "typescript": "^5.3.3"
+    "prettier": "^3.4.2",
+    "rollup": "^4.28.0",
+    "ts-jest": "^29.2.5",
+    "tslib": "^2.8.1",
+    "typescript": "^5.7.2"
   },
   "keywords": [
     "JSON",

package.json

@@ -3,7 +3,7 @@ import resolve from "@rollup/plugin-node-resolve";
 import { babel } from "@rollup/plugin-babel";
 import replace from "@rollup/plugin-replace";
 import terser from "@rollup/plugin-terser";
-import pkg from "./package.json" assert { type: "json" };
+import pkg from "./package.json" with { type: "json" };
 
 const extensions = [".js", ".jsx", ".ts", ".tsx"];
 const name = "json_p3";

rollup.config.mjs

@@ -243,7 +243,11 @@ export class OpMove implements Op {
     }
 
     if (isArray(destParent)) {
-      destParent.splice(Number(destTarget), 0, sourceObj);
+      if (destTarget === "-") {
+        destParent.push(sourceObj);
+      } else {
+        destParent.splice(Number(destTarget), 0, sourceObj);
+      }
     } else if (isObject(destParent)) {
       destParent[destTarget] = sourceObj;
     } else {
@@ -298,12 +302,16 @@ export class OpCopy implements Op {
     }
 
     if (isArray(destParent)) {
-      destParent.splice(Number(destTarget), 0, this.deepCopy(sourceObj));
+      if (destTarget === "-") {
+        destParent.push(this.deepCopy(sourceObj));
+      } else {
+        destParent.splice(Number(destTarget), 0, this.deepCopy(sourceObj));
+      }
     } else if (isObject(destParent)) {
       destParent[destTarget] = this.deepCopy(sourceObj);
     } else {
       throw new JSONPatchError(
-        `unexpected operation on '${typeof parent}' (${this.name}:${index})`,
+        `unexpected operation on '${typeof destParent}' (${this.name}:${index})`,
       );
     }
 

src/patch/patch.ts

@@ -26,7 +26,10 @@ export class LRUCache<K, V> extends Map<K, V> {
     if (this.has(key)) {
       this.delete(key);
     } else if (this.size >= this.maxSize) {
-      this.delete(this.first());
+      const first = this.first();
+      if (first !== undefined) {
+        this.delete(first);
+      }
     }
     return super.set(key, value);
   }

src/path/lru_cache.ts

@@ -142,4 +142,19 @@ describe("JSON Patch", () => {
       '"bar/" pointers must start with a slash or be the empty string (add:0)',
     );
   });
+  test("move, end of array", () => {
+    const data = { foo: { bar: [1, 2, 3] }, a: "b" };
+    const patch = new JSONPatch().move("/a", "/foo/bar/-");
+    expect(patch.apply(data)).toStrictEqual({
+      foo: { bar: [1, 2, 3, "b"] },
+    });
+  });
+  test("copy, end of array", () => {
+    const data = { foo: { bar: [1, 2, 3] }, a: "b" };
+    const patch = new JSONPatch().copy("/a", "/foo/bar/-");
+    expect(patch.apply(data)).toStrictEqual({
+      foo: { bar: [1, 2, 3, "b"] },
+      a: "b",
+    });
+  });
 });