Add mode to throw on invalid property access

mozilla · Jun 28, 2022 · c25502a · c25502a
1 parent 3d09092
commit c25502a
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Showing 2 changed files with 10 additions and 1 deletion.
diff --git a/lib/Jexl.js b/lib/Jexl.js
@@ -14,10 +14,11 @@ var Evaluator = require("./evaluator/Evaluator"),
  * xpath-like drilldown into native Javascript objects.
  * @constructor
  */
-function Jexl() {
+function Jexl(throwOnMissingProp = false) {
   this._customGrammar = null;
   this._lexer = null;
   this._transforms = {};
+  this._throwOnMissingProp = throwOnMissingProp;
 }
 
 /**

diff --git a/lib/evaluator/handlers.js b/lib/evaluator/handlers.js
@@ -83,6 +83,14 @@ exports.FilterExpression = function(ast) {
 exports.Identifier = function(ast) {
   if (ast.from) {
     return this.eval(ast.from).then(function(context) {
+      if (
+        this._throwOnMissingProp &&
+        !Object.hasOwnProperty(context, ast.value)
+      ) {
+        throw new Error(
+          `property does not have an identifier named ${ast.value}`
+        );
+      }
       if (Array.isArray(context)) context = context[0];
       if (context === undefined) return undefined;
       return context[ast.value];