- Fix: Allow empty string key (without parent selector)

Author: brettz9

src/jsonpath.js

@@ -273,7 +273,7 @@ JSONPath.prototype.evaluate = function (
     json = json || this.json;
     expr = expr || this.path;
     if (expr && typeof expr === 'object' && !Array.isArray(expr)) {
-        if (!expr.path) {
+        if (!expr.path && expr.path !== '') {
             throw new TypeError(
                 'You must supply a "path" property when providing an object ' +
                 'argument to JSONPath.evaluate().'
@@ -313,7 +313,7 @@ JSONPath.prototype.evaluate = function (
     if (Array.isArray(expr)) {
         expr = JSONPath.toPathString(expr);
     }
-    if (!expr || !json) {
+    if ((!expr && expr !== '') || !json) {
         return undefined;
     }
     this._obj = json;

test/test.path_expressions.js

@@ -79,4 +79,13 @@ describe('JSONPath - Path expressions', function () {
         const result = jsonpath({json, path: "$.store.book[*]['application/vnd.wordperfect']"});
         assert.deepEqual(result, expected);
     });
+
+    it('empty string key', () => {
+        const jsonSimple = {
+            '': null
+        };
+        const expected = null;
+        const result = jsonpath({json: jsonSimple, path: '', wrap: false});
+        assert.deepEqual(result, expected);
+    });
 });