Implement full long reflection

This makes maxLength and minLength have the precisely correct semantics for HTMLInputElement and HTMLTextAreaElement. And the code is now fully generated, instead of hand-coded.

lib/jsdom/living/nodes/HTMLInputElement-impl.js

@@ -748,35 +748,6 @@ class HTMLInputElementImpl extends HTMLElementImpl {
     return null;
   }
 
-  // Reflected IDL attribute does not care about whether the content attribute applies.
-  get maxLength() {
-    if (!this.hasAttributeNS(null, "maxlength")) {
-      return 524288; // stole this from chrome
-    }
-    return parseInt(this.getAttributeNS(null, "maxlength"));
-  }
-
-  set maxLength(value) {
-    if (value < 0) {
-      throw DOMException.create(this._globalObject, ["The index is not in the allowed range.", "IndexSizeError"]);
-    }
-    this.setAttributeNS(null, "maxlength", String(value));
-  }
-
-  get minLength() {
-    if (!this.hasAttributeNS(null, "minlength")) {
-      return 0;
-    }
-    return parseInt(this.getAttributeNS(null, "minlength"));
-  }
-
-  set minLength(value) {
-    if (value < 0) {
-      throw DOMException.create(this._globalObject, ["The index is not in the allowed range.", "IndexSizeError"]);
-    }
-    this.setAttributeNS(null, "minlength", String(value));
-  }
-
   get size() {
     if (!this.hasAttributeNS(null, "size")) {
       return 20;

lib/jsdom/living/nodes/HTMLInputElement.webidl

@@ -22,9 +22,9 @@ interface HTMLInputElement : HTMLElement {
   [CEReactions, Reflect] attribute DOMString inputMode;
   readonly attribute HTMLElement? list;
   [CEReactions, Reflect] attribute DOMString max;
-  [CEReactions] attribute long maxLength;
+  [CEReactions, ReflectNonNegative] attribute long maxLength;
   [CEReactions, Reflect] attribute DOMString min;
-  [CEReactions] attribute long minLength;
+  [CEReactions, ReflectNonNegative] attribute long minLength;
   [CEReactions, Reflect] attribute boolean multiple;
   [CEReactions, Reflect] attribute DOMString name;
   [CEReactions, Reflect] attribute DOMString pattern;

lib/jsdom/living/nodes/HTMLTextAreaElement.webidl

@@ -9,8 +9,8 @@ interface HTMLTextAreaElement : HTMLElement {
   [CEReactions, Reflect] attribute boolean disabled;
   readonly attribute HTMLFormElement? form;
   [CEReactions, Reflect] attribute DOMString inputMode;
-  [CEReactions, Reflect] attribute long maxLength; // TODO limited to only non-negative numbers
-  [CEReactions, Reflect] attribute long minLength; // TODO limited to only non-negative numbers
+  [CEReactions, ReflectNonNegative] attribute long maxLength;
+  [CEReactions, ReflectNonNegative] attribute long minLength;
   [CEReactions, Reflect] attribute DOMString name;
   [CEReactions, Reflect] attribute DOMString placeholder;
   [CEReactions, Reflect] attribute boolean readOnly;

scripts/webidl/convert.js

@@ -39,10 +39,16 @@ const transformer = new Webidl2js({
   },
   // https://html.spec.whatwg.org/multipage/common-dom-interfaces.html#reflecting-content-attributes-in-idl-attributes
   processReflect(idl, implObj) {
-    const reflectAttr = idl.extAttrs.find(attr => attr.name === "Reflect");
-    const attrName = (reflectAttr && reflectAttr.rhs && JSON.parse(reflectAttr.rhs.value)) || idl.name.toLowerCase();
+    const reflectAttr = idl.extAttrs.find(
+      attr => attr.name === "Reflect" || attr.name === "ReflectURL" || attr.name === "ReflectNonNegative"
+    );
+    const attrName = reflectAttr?.rhs ? JSON.parse(reflectAttr.rhs.value) : idl.name.toLowerCase();
 
-    if (idl.extAttrs.find(attr => attr.name === "ReflectURL")) {
+    // TODO: [ReflectDefault] is only used for `long` right now; also use it for `unsigned long` and `double`.
+    const reflectDefaultAttr = idl.extAttrs.find(attr => attr.name === "ReflectDefault");
+    const reflectDefault = reflectDefaultAttr?.rhs ? JSON.parse(reflectDefaultAttr.rhs.value) : undefined;
+
+    if (reflectAttr.name === "ReflectURL") {
       // Allow DOMString also due to https://github.com/whatwg/html/issues/5241.
       if (!isSimpleIDLType(idl.idlType, "USVString") && !isSimpleIDLType(idl.idlType, "DOMString")) {
         throw new Error("[ReflectURL] specified on non-USV/DOMString attribute");
@@ -68,6 +74,13 @@ const transformer = new Webidl2js({
       };
     }
 
+    if (reflectAttr.name === "ReflectNonNegative") {
+      if (!isSimpleIDLType(idl.idlType, "long")) {
+        throw new Error("[ReflectNonNegative] specified on non-long attribute");
+      }
+      // We'll actually do the processing in the long case, later.
+    }
+
     if (isSimpleIDLType(idl.idlType, "DOMString") || isSimpleIDLType(idl.idlType, "USVString")) {
       if (idl.idlType.nullable) {
         // Nonstandard; see https://github.com/whatwg/html/issues/10037. This passes the WPTs though.
@@ -113,18 +126,46 @@ const transformer = new Webidl2js({
     }
 
     if (isSimpleIDLType(idl.idlType, "long")) {
-      const parseInteger = this.addImport("../helpers/strings", "parseInteger");
+      const parser = this.addImport(
+        "../helpers/strings",
+        reflectAttr.name === "ReflectNonNegative" ? "parseNonNegativeInteger" : "parseInteger"
+      );
+
+      let defaultValue;
+      if (reflectDefault !== undefined) {
+        defaultValue = reflectDefault;
+      } else if (reflectAttr.name === "ReflectNonNegative") {
+        defaultValue = -1;
+      } else {
+        defaultValue = 0;
+      }
+
+      let setterPrefix = "";
+      if (reflectAttr.name === "ReflectNonNegative") {
+        const createDOMException = this.addImport("./DOMException", "create");
+        setterPrefix = `
+          if (V < 0) {
+            throw ${createDOMException}(
+              globalObject,
+              [\`The negative value \${V} cannot be set for the ${idl.name} property.\`, "IndexSizeError"]
+            );
+          }
+        `;
+      }
 
       return {
         get: `
           let value = ${implObj}._reflectGetTheContentAttribute("${attrName}");
-          if (value === null) {
-            return 0;
+          if (value !== null) {
+            value = ${parser}(value);
+            if (value !== null && conversions.long(value) === value) {
+              return value;
+            }
           }
-          value = ${parseInteger}(value);
-          return value !== null && conversions.long(value) === value ? value : 0;
+          return ${defaultValue};
         `,
         set: `
+          ${setterPrefix}
           ${implObj}._reflectSetTheContentAttribute("${attrName}", String(V));
         `
       };

test/web-platform-tests/to-run.yaml

@@ -1190,8 +1190,6 @@ input-type-button.html: [fail, Depends on offsetWidth]
 input-type-change-value.html: [fail, Unknown]
 input-type-checkbox-switch.tentative.window.html: [fail, Unknown]
 input-untrusted-key-event.html: [fail-slow, Not implemented]
-maxlength.html: [fail, Reflection not implemented correctly]
-minlength.html: [fail, Reflection not implemented correctly]
 pattern_attribute_v_flag.html: [fail, Unknown]
 radio-disconnected-group-owner.html: [fail, Unknown]
 range-2.html: [fail, step attribute not yet implemented]
@@ -1242,8 +1240,6 @@ show-picker-cross-origin-iframe.tentative.html: [timeout, Unknown]
 
 DIR: html/semantics/forms/the-textarea-element
 
-textarea-maxlength.html: [fail, Unknown]
-textarea-minlength.html: [fail, Unknown]
 textarea-placeholder-lineheight.html: [fail, getBoundingClientRect() is not implemented]
 wrap-enumerated-ascii-case-insensitive.html: [timeout, Unknown]