Make variable accessible after initialization

discoveryjs · Dec 7, 2019 · 690dd9e · 690dd9e
1 parent 6814e90
commit 690dd9e
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Showing 2 changed files with 28 additions and 5 deletions.
diff --git a/src/compile.js b/src/compile.js
@@ -338,9 +338,11 @@ module.exports = function compile(ast, suggestRanges = [], statMode = false) {
                     put('$');
                     walk(node.name);
                 } else {
-                    put('/*bad ref: $');
+                    put('typeof $');
                     walk(node.name);
-                    put('*/undefined');
+                    put('!=="undefined"?$');
+                    walk(node.name);
+                    put(':undefined');
                 }
                 break;
 

diff --git a/test/variables.js b/test/variables.js
@@ -50,14 +50,35 @@ describe('definitions', () => {
         );
     });
 
+    it('should return undefined when refer to never defined variable', () => {
+        assert.deepEqual(
+            query('$a:$b;$a')(),
+            undefined
+        );
+    });
+
+    it('should throw when access before initialization', () => {
+        assert.throws(
+            () => query('$a:$a;')(),
+            /\$a is not defined|Cannot access '\$a' before initialization/
+        );
+    });
+
+    it('should return a value when access after initialization', () => {
+        assert.deepEqual(
+            query('$a:=>foo.map($a) or foo;{ foo: { foo: 42 }}.map($a)')(),
+            42
+        );
+    });
+
     it('should throw when redefine a variable defined in the same scope', () => {
         assert.throws(
             () => query('$a;$a;')(),
-            new RegExp('Identifier \'\\$a\' has already been declared')
+            /Identifier '\$a' has already been declared/
         );
     });
 
-    it('should not throw when variables with the same name defined in different scopes', () => {
+    it('should not throw when variables with the same name defined in another scope', () => {
         assert.doesNotThrow(
             () => query('$a;.($b;) + .($b;)')()
         );
@@ -66,7 +87,7 @@ describe('definitions', () => {
     it('should throw when redefine a variable defined in parent scope', () => {
         assert.throws(
             () => query('$a;.($a;)')(),
-            new RegExp('Identifier \'\\$a\' has already been declared')
+            /Identifier '\$a' has already been declared/
         );
     });