Implement Document.getElementById() without using xpath

rbri · rbri · commit 380bf3e23c53 · 2025-02-16T12:59:22.000+01:00
diff --git a/src/main/java/org/htmlunit/javascript/host/dom/Document.java b/src/main/java/org/htmlunit/javascript/host/dom/Document.java
@@ -3519,9 +3519,10 @@ public HTMLCollection getAll() {
     @JsxFunction
     public HtmlUnitScriptable getElementById(final String id) {
         final DomNode domNode = getDomNodeOrDie();
-        final Object domElement = domNode.getFirstByXPath("//*[@id = \"" + id + "\"]");
-        if (domElement != null) {
-            return ((DomElement) domElement).getScriptableObject();
+        for (final DomElement descendant : domNode.getDomElementDescendants()) {
+            if (descendant instanceof HtmlElement && id.equals(((HtmlElement) descendant).getId())) {
+                return descendant.getScriptableObject();
+            }
         }
         return null;
     }
diff --git a/src/test/java/org/htmlunit/javascript/host/dom/Document2Test.java b/src/test/java/org/htmlunit/javascript/host/dom/Document2Test.java
@@ -496,6 +496,32 @@ public void getElementById() throws Exception {
         loadPageVerifyTitle2(html);
     }
 
+
+    /**
+     * @throws Exception if the test fails
+     */
+    @Test
+    @Alerts({"zero", "udef"})
+    public void getElementByIdNull() throws Exception {
+        final String html
+            = "<html><head>\n"
+            + "<script>\n"
+            + LOG_TITLE_FUNCTION
+            + "function doTest() {\n"
+            + "  log(top.document.getElementById(null).name);\n"
+            + "  log(top.document.getElementById(undefined).name);\n"
+            + "}\n"
+            + "</script></head>\n"
+            + "<body onload='doTest()'>\n"
+            + "<form id='form1'>\n"
+            + "<input id='undefined' name='udef' type='text' value='u' />\n"
+            + "<input id='null' name='zero' type='text' value='n' />\n"
+            + "</form>\n"
+            + "</body></html>";
+
+        loadPageVerifyTitle2(html);
+    }
+
     /**
      * @throws Exception if the test fails
      */

Original file line number	Diff line number	Diff line change
`@@ -3519,9 +3519,10 @@ public HTMLCollection getAll() {`
`3519`	`3519`	`@JsxFunction`
`3520`	`3520`	`public HtmlUnitScriptable getElementById(final String id) {`
`3521`	`3521`	`final DomNode domNode = getDomNodeOrDie();`
`3522`		`- final Object domElement = domNode.getFirstByXPath("//*[@id = \"" + id + "\"]");`
`3523`		`- if (domElement != null) {`
`3524`		`- return ((DomElement) domElement).getScriptableObject();`
	`3522`	`+ for (final DomElement descendant : domNode.getDomElementDescendants()) {`
	`3523`	`+ if (descendant instanceof HtmlElement && id.equals(((HtmlElement) descendant).getId())) {`
	`3524`	`+ return descendant.getScriptableObject();`
	`3525`	`+ }`
`3525`	`3526`	`}`
`3526`	`3527`	`return null;`
`3527`	`3528`	`}`