Handle unspecified nodes

goto100 · Dec 16, 2023 · 35dabde · 35dabde
1 parent 3ce4730
commit 35dabde
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Showing 2 changed files with 27 additions and 10 deletions.
diff --git a/test.js b/test.js
@@ -1304,23 +1304,31 @@ describe('xpath', () => {
     describe('error handling', () => {
         it('should reject unspecified expression', () => {
             for (let expr of [null, undefined, '']) {
-                assert.throws(() => {
-                    xpath.parse(expr);
-                }, {
-                    message: 'XPath expression unspecified'
+                assert.throws(() => xpath.parse(expr), {
+                    message: 'XPath expression unspecified',
                 });
             }
         });
 
         it('should reject non-nodes', () => {
             for (let node of ['<n />', 0, 45, true, false, [], {}]) {
-                assert.throws(() => {
-                    xpath.parse('/*').select({ node });
-                }, {
-                    message: 'Context node does not appear to be a valid DOM node.'
+                assert.throws(() => xpath.parse('/*').select({ node }), {
+                    message: 'Context node does not appear to be a valid DOM node.',
                 });
             }
         });
+
+        it('should handle unspecified nodes', () => {
+            assert.throws(
+                () => xpath.parse('my:field').select(), {
+                message: 'Context node not found when evaluating XPath step: child::my:field',
+            });
+
+            assert.throws(
+                () => xpath.parse('/*').select(), {
+                message: 'Context node not found when determining document root.',
+            });
+        })
     });
 
     describe('Node type tests', () => {

diff --git a/xpath.js b/xpath.js
@@ -1855,14 +1855,20 @@ var xpath = (typeof exports === 'undefined') ? {} : exports;
     PathExpr.getRoot = function (xpc, nodes) {
         var firstNode = nodes[0];
 
-        if (firstNode.nodeType === NodeTypes.DOCUMENT_NODE) {
+        // xpc.virtualRoot could possibly provide a root even if firstNode is null,
+        // so using a guard here instead of throwing.
+        if (firstNode && firstNode.nodeType === NodeTypes.DOCUMENT_NODE) {
             return firstNode;
         }
 
         if (xpc.virtualRoot) {
             return xpc.virtualRoot;
         }
 
+        if (!firstNode) {
+            throw new Error('Context node not found when determining document root.');
+        }
+
         var ownerDoc = firstNode.ownerDocument;
 
         if (ownerDoc) {
@@ -1892,7 +1898,10 @@ var xpath = (typeof exports === 'undefined') ? {} : exports;
     };
 
     PathExpr.applyStep = function (step, xpc, node) {
-        var self = this;
+        if (!node) {
+            throw new Error('Context node not found when evaluating XPath step: ' + step);
+        }
+
         var newNodes = [];
         xpc.contextNode = node;