fix: distinguish malformed JSON from partial arrays

src/index.test.ts

@@ -0,0 +1,28 @@
+import { describe, expect, it } from "vitest";
+import { MalformedJSON, parse } from "./index";
+
+describe("malformed JSON handling", () => {
+    it("throws for malformed numbers inside arrays", () => {
+        expect(() => parse("[1, .05, 2]")).toThrow(MalformedJSON);
+    });
+
+    it("throws for malformed numbers inside objects", () => {
+        expect(() => parse('{"a": .05, "b": 2}')).toThrow(MalformedJSON);
+    });
+
+    it("keeps parsing after an empty array with spaces", () => {
+        expect(parse('[{"id":1,"arr":["hello"]},{"id":2,"arr":[        ],"more":"yaya"},{"id":3,"arr":["!"]}]')).toEqual([
+            { id: 1, arr: ["hello"] },
+            { id: 2, arr: [], more: "yaya" },
+            { id: 3, arr: ["!"] },
+        ]);
+    });
+
+    it("keeps parsing after an object comma with spaces", () => {
+        expect(parse('{"a":1,   }')).toEqual({ a: 1 });
+    });
+
+    it("keeps parsing after an array comma with spaces", () => {
+        expect(parse("[1,   ]")).toEqual([1]);
+    });
+});

src/index.ts

@@ -35,6 +35,8 @@ const _parseJSON = (jsonString: string, allow: number) => {
         throw new MalformedJSON(`${msg} at position ${index}`);
     };
 
+    const isPartialJSON = (e: unknown) => e instanceof PartialJSON;
+
     const parseAny: () => any = () => {
         skipBlank();
         if (index >= length) markPartialJSON("Unexpected end of input");
@@ -108,32 +110,42 @@ const _parseJSON = (jsonString: string, allow: number) => {
                     const value = parseAny();
                     obj[key] = value;
                 } catch (e) {
-                    if (Allow.OBJ & allow) return obj;
-                    else throw e;
+                    if (Allow.OBJ & allow && isPartialJSON(e)) return obj;
+                    throw e;
                 }
                 skipBlank();
-                if (jsonString[index] === ",") index++; // skip comma
+                if (jsonString[index] === ",") {
+                    index++; // skip comma
+                    skipBlank();
+                }
             }
         } catch (e) {
+            if (!isPartialJSON(e)) {
+                if (index >= length) markPartialJSON("Expected '}' at end of object");
+                throw e;
+            }
             if (Allow.OBJ & allow) return obj;
-            else markPartialJSON("Expected '}' at end of object");
+            markPartialJSON("Expected '}' at end of object");
         }
         index++; // skip final brace
         return obj;
     };
 
     const parseArr = () => {
         index++; // skip initial bracket
+        skipBlank();
         const arr = [];
         try {
             while (jsonString[index] !== "]") {
                 arr.push(parseAny());
                 skipBlank();
                 if (jsonString[index] === ",") {
                     index++; // skip comma
+                    skipBlank();
                 }
             }
         } catch (e) {
+            if (!isPartialJSON(e)) throw e;
             if (Allow.ARR & allow) {
                 return arr;
             }