Return null or undefined if supplied; deal with nullish values by requiring "new" by avoided

lib/jsonpath.js

@@ -34,8 +34,16 @@ function push (arr, elem) {arr = arr.slice(); arr.push(elem); return arr;}
 function unshift (elem, arr) {arr = arr.slice(); arr.unshift(elem); return arr;}
 
 function JSONPath (opts, obj, expr) {
-    if (!(this instanceof JSONPath)) { // Make "new" optional
-        return new JSONPath(opts, obj, expr);
+    if (!(this instanceof JSONPath)) {
+        try {
+            return new JSONPath(opts, obj, expr);
+        }
+        catch (e) {
+            if (!e.avoidNew) {
+                throw e;
+            }
+            return e.value;
+        }
     }
 
     opts = opts || {};
@@ -46,7 +54,10 @@ function JSONPath (opts, obj, expr) {
     this.sandbox = opts.sandbox || {};
 
     if (opts.autostart !== false) {
-        return this.evaluate((objArgs ? opts.json : obj), (objArgs ? opts.path : expr));
+        var ret = this.evaluate((objArgs ? opts.json : obj), (objArgs ? opts.path : expr));
+        if (!ret) {
+            throw {avoidNew: true, value: ret, message: "JSONPath should not be called with 'new'"};
+        }
     }
 }
 
@@ -213,7 +224,7 @@ JSONPath.prototype._eval = function (code, _v, _vname, path) {
 
 // For backward compatibility (deprecated)
 JSONPath.eval = function (obj, expr, opts) {
-    return new JSONPath(opts, obj, expr);
+    return JSONPath(opts, obj, expr);
 };
 
 if (typeof module === 'undefined') {