Move selection to end when textarea value is assigned

Issue #19171

components/script/dom/htmltextareaelement.rs

@@ -34,7 +34,7 @@ use std::default::Default;
 use std::ops::Range;
 use style::attr::AttrValue;
 use style::element_state::ElementState;
-use textinput::{KeyReaction, Lines, SelectionDirection, TextInput};
+use textinput::{Direction, KeyReaction, Lines, Selection, SelectionDirection, TextInput};
 
 #[dom_struct]
 pub struct HTMLTextAreaElement {
@@ -232,10 +232,25 @@ impl HTMLTextAreaElementMethods for HTMLTextAreaElement {
 
     // https://html.spec.whatwg.org/multipage/#dom-textarea-value
     fn SetValue(&self, value: DOMString) {
-        // TODO move the cursor to the end of the field
-        self.textinput.borrow_mut().set_content(value);
+        let mut textinput = self.textinput.borrow_mut();
+
+        // Step 1
+        let old_value = textinput.get_content();
+        let old_selection = textinput.selection_begin;
+
+        // Step 2
+        textinput.set_content(value);
+
+        // Step 3
         self.value_changed.set(true);
 
+        if old_value != textinput.get_content() {
+            // Step 4
+            textinput.adjust_horizontal_to_limit(Direction::Forward, Selection::NotSelected);
+        } else {
+            textinput.selection_begin = old_selection;
+        }
+
         self.upcast::<Node>().dirty(NodeDamage::OtherNodeDamage);
     }
 

tests/wpt/metadata/MANIFEST.json

@@ -542604,7 +542604,7 @@
    "testharness"
   ],
   "html/semantics/forms/textfieldselection/selection-value-interactions.html": [
-   "c568d7fe10cb4c2071b5d38530ad601988a789ea",
+   "39fe9646bbc2741e9bd3296d4e01513c99106151",
    "testharness"
   ],
   "html/semantics/forms/textfieldselection/selection.html": [

tests/wpt/metadata/html/semantics/forms/textfieldselection/selection-start-end.html.ini

@@ -3,33 +3,3 @@
   [Setting selectionStart to a value larger than selectionEnd should increase selectionEnd]
     expected: FAIL
 
-  [Setting selectionEnd to a value smaller than selectionStart should decrease selectionStart]
-    expected: FAIL
-
-  [selectionStart edge-case values]
-    expected: FAIL
-
-  [Initial .value set on textarea-appended should set selectionStart to end of value]
-    expected: FAIL
-
-  [Initial .value set on textarea-not-appended should set selectionStart to end of value]
-    expected: FAIL
-
-  [Initial .value set on textarea-appended-prefocused should set selectionStart to end of value]
-    expected: FAIL
-
-  [Initial .value set on textarea-not-appended-prefocused should set selectionStart to end of value]
-    expected: FAIL
-
-  [Initial .value set on textarea-appended should set selectionEnd to end of value]
-    expected: FAIL
-
-  [Initial .value set on textarea-not-appended should set selectionEnd to end of value]
-    expected: FAIL
-
-  [Initial .value set on textarea-appended-prefocused should set selectionEnd to end of value]
-    expected: FAIL
-
-  [Initial .value set on textarea-not-appended-prefocused should set selectionEnd to end of value]
-    expected: FAIL
-

tests/wpt/metadata/html/semantics/forms/textfieldselection/selection.html.ini

@@ -36,15 +36,9 @@
   [test SelectionStart offset for textarea that is appended]
     expected: FAIL
 
-  [test SelectionStart offset for textarea that is  not appended]
-    expected: FAIL
-
   [test SelectionEnd offset for input that is appended]
     expected: FAIL
 
   [test SelectionEnd offset for textarea that is appended]
     expected: FAIL
 
-  [test SelectionEnd offset for textarea that is  not appended]
-    expected: FAIL
-

tests/wpt/web-platform-tests/html/semantics/forms/textfieldselection/selection-value-interactions.html

@@ -97,22 +97,31 @@
     var el = document.createElement(tag);
     document.body.appendChild(el);
     this.add_cleanup(() => el.remove());
-    el.value = "";
-    assert_equals(el.selectionStart, el.value.length,
-                 "element.selectionStart should be value.length");
-    assert_equals(el.selectionEnd, el.value.length,
-                  "element.selectionEnd should be value.length");
-    el.value = "foo";
-    assert_equals(el.selectionStart, el.value.length,
-                 "element.selectionStart should be value.length");
-    assert_equals(el.selectionEnd, el.value.length,
-                  "element.selectionEnd should be value.length");
-    el.value = "foobar";
-    assert_equals(el.selectionStart, el.value.length,
-                 "element.selectionStart should be value.length");
-    assert_equals(el.selectionEnd, el.value.length,
-                  "element.selectionEnd should be value.length");
-  }, `selection is always collapsed to the end after setting values on ${tag}`);
+
+    for (let val of ["", "foo", "foobar"]) {
+      el.value = val;
+      assert_equals(el.selectionStart, val.length,
+                   "element.selectionStart should be value.length");
+      assert_equals(el.selectionEnd, val.length,
+                    "element.selectionEnd should be value.length");
+    }
+  }, `selection is collapsed to the end after changing values on ${tag}`);
+
+  test(function() {
+    var el = document.createElement(tag);
+    document.body.appendChild(el);
+    this.add_cleanup(() => el.remove());
+
+    el.value = "foobar"
+    el.selectionStart = 2
+    el.selectionEnd = 4
+    el.value = "foobar"
+
+    assert_equals(el.selectionStart, 2,
+                  "element.selectionStart should be unchanged");
+    assert_equals(el.selectionEnd, 4,
+                  "element.selectionEnd should be unchanged");
+  }, `selection is not collapsed to the end when value is set to its existing value on ${tag}`);
 }
 
 </script>