diff --git a/changelog_unreleased/javascript/12070.md b/changelog_unreleased/javascript/12070.md
new file mode 100644
index 000000000..66bf7183e
--- /dev/null
+++ b/changelog_unreleased/javascript/12070.md
@@ -0,0 +1,17 @@
+#### Print comments for parenthesized TS keyword types with `babel-ts` parser (#12070 by @sosukesuzuki)
+
+<!-- prettier-ignore -->
+```ts
+// Input
+let foo: (
+   // comment
+   never
+);
+
+// Prettier stable
+Error: Comment "comment" was not printed. Please report this error!
+
+// Prettier main
+let foo: // comment
+never;
+```
diff --git a/src/language-html/ast.js b/src/language-html/ast.js
index cf67d691a..913960a17 100644
--- a/src/language-html/ast.js
+++ b/src/language-html/ast.js
@@ -26,11 +26,13 @@ class Node {
     if (nodes !== this[key]) {
       this[key] = cloneAndUpdateNodes(nodes, this);
       if (key === "attrs") {
-        setNonEnumerableProperties(this, {
-          attrMap: Object.fromEntries(
+        setNonEnumerableProperty(
+          this,
+          "attrMap",
+          Object.fromEntries(
             this[key].map((attr) => [attr.fullName, attr.value])
-          ),
-        });
+          )
+        );
       }
     }
   }
@@ -45,7 +47,8 @@ class Node {
         const mappedNodes = mapNodesIfChanged(nodes, (node) => node.map(fn));
         if (newNode !== nodes) {
           if (!newNode) {
-            newNode = new Node();
+            // @ts-expect-error
+            newNode = new Node({ parent: this.parent });
           }
           newNode._setNodes(NODES_KEY, mappedNodes);
         }
@@ -58,15 +61,6 @@ class Node {
           newNode[key] = this[key];
         }
       }
-      // @ts-expect-error
-      const { index, siblings, prev, next, parent } = this;
-      setNonEnumerableProperties(newNode, {
-        index,
-        siblings,
-        prev,
-        next,
-        parent,
-      });
     }
 
     return fn(newNode || this);
@@ -85,10 +79,37 @@ class Node {
   }
 
   /**
-   * @param {Object} [overrides]
+   * @param {Node} [target]
+   * @param {Object} [node]
    */
-  clone(overrides) {
-    return new Node(overrides ? { ...this, ...overrides } : this);
+  insertChildBefore(target, node) {
+    const newNode = new Node({ ...node, parent: this });
+
+    // @ts-expect-error
+    this.children.splice(this.children.indexOf(target), 0, newNode);
+  }
+
+  /**
+   * @param {Node} [child]
+   */
+  removeChild(child) {
+    // @ts-expect-error
+    this.children.splice(this.children.indexOf(child), 1);
+  }
+
+  /**
+   * @param {Node} [target]
+   * @param {Object} [node]
+   */
+  replaceChild(target, node) {
+    const newNode = new Node({ ...node, parent: this });
+
+    // @ts-expect-error
+    this.children[this.children.indexOf(target)] = newNode;
+  }
+
+  clone() {
+    return new Node(this);
   }
 
   /**
@@ -108,6 +129,24 @@ class Node {
     return isNonEmptyArray(this.children) ? getLast(this.children) : null;
   }
 
+  get prev() {
+    // @ts-expect-error
+    if (!this.parent) {
+      return null;
+    }
+    // @ts-expect-error
+    return this.parent.children[this.parent.children.indexOf(this) - 1];
+  }
+
+  get next() {
+    // @ts-expect-error
+    if (!this.parent) {
+      return null;
+    }
+    // @ts-expect-error
+    return this.parent.children[this.parent.children.indexOf(this) + 1];
+  }
+
   // for element and attribute
   get rawName() {
     // @ts-expect-error
@@ -128,38 +167,18 @@ function mapNodesIfChanged(nodes, fn) {
 
 function cloneAndUpdateNodes(nodes, parent) {
   const siblings = nodes.map((node) =>
-    node instanceof Node ? node.clone() : new Node(node)
+    node instanceof Node ? node.clone() : new Node({ ...node, parent })
   );
 
-  let prev = null;
-  let current = siblings[0];
-  let next = siblings[1] || null;
-
-  for (let index = 0; index < siblings.length; index++) {
-    setNonEnumerableProperties(current, {
-      index,
-      siblings,
-      prev,
-      next,
-      parent,
-    });
-    prev = current;
-    current = next;
-    next = siblings[index + 2] || null;
+  for (const sibling of siblings) {
+    sibling.parent = parent;
   }
 
   return siblings;
 }
 
-function setNonEnumerableProperties(obj, props) {
-  const descriptors = Object.fromEntries(
-    Object.entries(props).map(([key, value]) => [
-      key,
-      { value, enumerable: false },
-    ])
-  );
-
-  Object.defineProperties(obj, descriptors);
+function setNonEnumerableProperty(obj, key, value) {
+  Object.defineProperty(obj, key, { value, enumerable: false });
 }
 
 module.exports = {
diff --git a/src/language-html/clean.js b/src/language-html/clean.js
index fbfc73f2e..2d316486d 100644
--- a/src/language-html/clean.js
+++ b/src/language-html/clean.js
@@ -8,6 +8,7 @@ const ignoredProperties = new Set([
   "endSourceSpan",
   "nameSpan",
   "valueSpan",
+  "parent",
 ]);
 
 function clean(ast, newNode) {
diff --git a/src/language-html/parser-html.js b/src/language-html/parser-html.js
index 54bf9c2e3..dd5c1e968 100644
--- a/src/language-html/parser-html.js
+++ b/src/language-html/parser-html.js
@@ -334,13 +334,16 @@ function _parse(text, options, parserOptions, shouldParseFrontMatter = true) {
       parserOptions,
       false
     );
+    // @ts-expect-error
     subAst.sourceSpan = new ParseSourceSpan(
       startSpan,
+      // @ts-expect-error
       getLast(subAst.children).sourceSpan.end
     );
+    // @ts-expect-error
     const firstText = subAst.children[0];
     if (firstText.length === offset) {
-      /* istanbul ignore next */
+      /* istanbul ignore next */ // @ts-expect-error
       subAst.children.shift();
     } else {
       firstText.sourceSpan = new ParseSourceSpan(
@@ -352,19 +355,19 @@ function _parse(text, options, parserOptions, shouldParseFrontMatter = true) {
     return subAst;
   };
 
-  return ast.map((node) => {
+  ast.walk((node) => {
     if (node.type === "comment") {
       const ieConditionalComment = parseIeConditionalComment(
         node,
         parseSubHtml
       );
       if (ieConditionalComment) {
-        return ieConditionalComment;
+        node.parent.replaceChild(node, ieConditionalComment);
       }
     }
-
-    return node;
   });
+
+  return ast;
 }
 
 /**
diff --git a/src/language-html/print-preprocess.js b/src/language-html/print-preprocess.js
index 969e75372..a9c01d006 100644
--- a/src/language-html/print-preprocess.js
+++ b/src/language-html/print-preprocess.js
@@ -3,7 +3,6 @@
 const {
   ParseSourceSpan,
 } = require("angular-html-parser/lib/compiler/src/parse_util");
-const getLast = require("../utils/get-last.js");
 const {
   htmlTrim,
   getLeadingAndTrailingHtmlWhitespace,
@@ -31,11 +30,10 @@ const PREPROCESS_PIPELINE = [
 ];
 
 function preprocess(ast, options) {
-  const res = ast.map((node) => node);
   for (const fn of PREPROCESS_PIPELINE) {
-    fn(res, options);
+    fn(ast, options);
   }
-  return res;
+  return ast;
 }
 
 function removeIgnorableFirstLf(ast /*, options */) {
@@ -47,12 +45,12 @@ function removeIgnorableFirstLf(ast /*, options */) {
       node.children[0].type === "text" &&
       node.children[0].value[0] === "\n"
     ) {
-      const [text, ...rest] = node.children;
-      node.setChildren(
-        text.value.length === 1
-          ? rest
-          : [text.clone({ value: text.value.slice(1) }), ...rest]
-      );
+      const text = node.children[0];
+      if (text.value.length === 1) {
+        node.removeChild(text);
+      } else {
+        text.value = text.value.slice(1);
+      }
     }
   });
 }
@@ -73,47 +71,32 @@ function mergeIfConditionalStartEndCommentIntoElementOpeningTag(
     node.firstChild.sourceSpan.start.offset === node.startSourceSpan.end.offset;
   ast.walk((node) => {
     if (node.children) {
-      const isTargetResults = node.children.map(isTarget);
-      if (isTargetResults.some(Boolean)) {
-        const newChildren = [];
-
-        for (let i = 0; i < node.children.length; i++) {
-          const child = node.children[i];
-
-          if (isTargetResults[i + 1]) {
-            // ieConditionalStartComment
-            continue;
-          }
-
-          if (isTargetResults[i]) {
-            const ieConditionalStartComment = child.prev;
-            const ieConditionalEndComment = child.firstChild;
-
-            const startSourceSpan = new ParseSourceSpan(
-              ieConditionalStartComment.sourceSpan.start,
-              ieConditionalEndComment.sourceSpan.end
-            );
-            const sourceSpan = new ParseSourceSpan(
-              startSourceSpan.start,
-              child.sourceSpan.end
-            );
-
-            newChildren.push(
-              child.clone({
-                condition: ieConditionalStartComment.condition,
-                sourceSpan,
-                startSourceSpan,
-                children: child.children.slice(1),
-              })
-            );
-
-            continue;
-          }
-
-          newChildren.push(child);
+      for (let i = 0; i < node.children.length; i++) {
+        const child = node.children[i];
+        if (!isTarget(child)) {
+          continue;
         }
 
-        node.setChildren(newChildren);
+        const ieConditionalStartComment = child.prev;
+        const ieConditionalEndComment = child.firstChild;
+
+        // ieConditionalStartComment
+        node.removeChild(ieConditionalStartComment);
+        i--; // because a node was removed
+
+        const startSourceSpan = new ParseSourceSpan(
+          ieConditionalStartComment.sourceSpan.start,
+          ieConditionalEndComment.sourceSpan.end
+        );
+        const sourceSpan = new ParseSourceSpan(
+          startSourceSpan.start,
+          child.sourceSpan.end
+        );
+
+        child.condition = ieConditionalStartComment.condition;
+        child.sourceSpan = sourceSpan;
+        child.startSourceSpan = startSourceSpan;
+        child.removeChild(ieConditionalEndComment);
       }
     }
   });
@@ -122,42 +105,31 @@ function mergeIfConditionalStartEndCommentIntoElementOpeningTag(
 function mergeNodeIntoText(ast, shouldMerge, getValue) {
   ast.walk((node) => {
     if (node.children) {
-      const shouldMergeResults = node.children.map(shouldMerge);
-      if (shouldMergeResults.some(Boolean)) {
-        const newChildren = [];
-        for (let i = 0; i < node.children.length; i++) {
-          const child = node.children[i];
+      for (let i = 0; i < node.children.length; i++) {
+        const child = node.children[i];
 
-          if (child.type !== "text" && !shouldMergeResults[i]) {
-            newChildren.push(child);
-            continue;
-          }
-
-          const newChild =
-            child.type === "text"
-              ? child
-              : child.clone({ type: "text", value: getValue(child) });
-
-          if (
-            newChildren.length === 0 ||
-            getLast(newChildren).type !== "text"
-          ) {
-            newChildren.push(newChild);
-            continue;
-          }
-
-          const lastChild = newChildren.pop();
-          newChildren.push(
-            lastChild.clone({
-              value: lastChild.value + newChild.value,
-              sourceSpan: new ParseSourceSpan(
-                lastChild.sourceSpan.start,
-                newChild.sourceSpan.end
-              ),
-            })
-          );
+        if (child.type !== "text" && !shouldMerge(child)) {
+          continue;
         }
-        node.setChildren(newChildren);
+
+        if (child.type !== "text") {
+          child.type = "text";
+          child.value = getValue(child);
+        }
+
+        const prevChild = child.prev;
+        if (!prevChild || prevChild.type !== "text") {
+          continue;
+        }
+
+        prevChild.value += child.value;
+        prevChild.sourceSpan = new ParseSourceSpan(
+          prevChild.sourceSpan.start,
+          child.sourceSpan.end
+        );
+
+        node.removeChild(child);
+        i--; // because a node was removed
       }
     }
   });
@@ -190,36 +162,29 @@ function mergeSimpleElementIntoText(ast /*, options */) {
     node.next.type === "text";
   ast.walk((node) => {
     if (node.children) {
-      const isSimpleElementResults = node.children.map(isSimpleElement);
-      if (isSimpleElementResults.some(Boolean)) {
-        const newChildren = [];
-        for (let i = 0; i < node.children.length; i++) {
-          const child = node.children[i];
-          if (isSimpleElementResults[i]) {
-            const lastChild = newChildren.pop();
-            const nextChild = node.children[++i];
-            const { isTrailingSpaceSensitive, hasTrailingSpaces } = nextChild;
-            newChildren.push(
-              lastChild.clone({
-                value:
-                  lastChild.value +
-                  `<${child.rawName}>` +
-                  child.firstChild.value +
-                  `</${child.rawName}>` +
-                  nextChild.value,
-                sourceSpan: new ParseSourceSpan(
-                  lastChild.sourceSpan.start,
-                  nextChild.sourceSpan.end
-                ),
-                isTrailingSpaceSensitive,
-                hasTrailingSpaces,
-              })
-            );
-          } else {
-            newChildren.push(child);
-          }
+      for (let i = 0; i < node.children.length; i++) {
+        const child = node.children[i];
+        if (!isSimpleElement(child)) {
+          continue;
         }
-        node.setChildren(newChildren);
+
+        const prevChild = child.prev;
+        const nextChild = child.next;
+        prevChild.value +=
+          `<${child.rawName}>` +
+          child.firstChild.value +
+          `</${child.rawName}>` +
+          nextChild.value;
+        prevChild.sourceSpan = new ParseSourceSpan(
+          prevChild.sourceSpan.start,
+          nextChild.sourceSpan.end
+        );
+        prevChild.isTrailingSpaceSensitive = nextChild.isTrailingSpaceSensitive;
+        prevChild.hasTrailingSpaces = nextChild.hasTrailingSpaces;
+
+        node.removeChild(child);
+        i--; // because a node was removed
+        node.removeChild(nextChild);
       }
     }
   });
@@ -236,11 +201,8 @@ function extractInterpolation(ast, options) {
       return;
     }
 
-    const newChildren = [];
-
     for (const child of node.children) {
       if (child.type !== "text") {
-        newChildren.push(child);
         continue;
       }
 
@@ -257,7 +219,7 @@ function extractInterpolation(ast, options) {
         if (i % 2 === 0) {
           endSourceSpan = startSourceSpan.moveBy(value.length);
           if (value.length > 0) {
-            newChildren.push({
+            node.insertChildBefore(child, {
               type: "text",
               value,
               sourceSpan: new ParseSourceSpan(startSourceSpan, endSourceSpan),
@@ -267,7 +229,7 @@ function extractInterpolation(ast, options) {
         }
 
         endSourceSpan = startSourceSpan.moveBy(value.length + 4); // `{{` + `}}`
-        newChildren.push({
+        node.insertChildBefore(child, {
           type: "interpolation",
           sourceSpan: new ParseSourceSpan(startSourceSpan, endSourceSpan),
           children:
@@ -285,9 +247,9 @@ function extractInterpolation(ast, options) {
                 ],
         });
       }
-    }
 
-    node.setChildren(newChildren);
+      node.removeChild(child);
+    }
   });
 }
 
@@ -298,7 +260,6 @@ function extractInterpolation(ast, options) {
  * - add `isWhitespaceSensitive`, `isIndentationSensitive` field for text nodes
  * - remove insensitive whitespaces
  */
-const WHITESPACE_NODE = { type: "whitespace" };
 function extractWhitespaces(ast /*, options*/) {
   ast.walk((node) => {
     if (!node.children) {
@@ -319,94 +280,91 @@ function extractWhitespaces(ast /*, options*/) {
     const isWhitespaceSensitive = isWhitespaceSensitiveNode(node);
     const isIndentationSensitive = isIndentationSensitiveNode(node);
 
-    node.setChildren(
-      node.children
-        // extract whitespace nodes
-        .flatMap((child) => {
-          if (child.type !== "text" || isWhitespaceSensitive) {
-            return child;
+    if (!isWhitespaceSensitive) {
+      for (let i = 0; i < node.children.length; i++) {
+        const child = node.children[i];
+        if (child.type !== "text") {
+          continue;
+        }
+
+        const { leadingWhitespace, text, trailingWhitespace } =
+          getLeadingAndTrailingHtmlWhitespace(child.value);
+
+        const prevChild = child.prev;
+        const nextChild = child.next;
+
+        if (!text) {
+          node.removeChild(child);
+          i--; // because a node was removed
+
+          if (leadingWhitespace || trailingWhitespace) {
+            if (prevChild) {
+              prevChild.hasTrailingSpaces = true;
+            }
+            if (nextChild) {
+              nextChild.hasLeadingSpaces = true;
+            }
           }
-
-          const localChildren = [];
-
-          const { leadingWhitespace, text, trailingWhitespace } =
-            getLeadingAndTrailingHtmlWhitespace(child.value);
+        } else {
+          child.value = text;
+          child.sourceSpan = new ParseSourceSpan(
+            child.sourceSpan.start.moveBy(leadingWhitespace.length),
+            child.sourceSpan.end.moveBy(-trailingWhitespace.length)
+          );
 
           if (leadingWhitespace) {
-            localChildren.push(WHITESPACE_NODE);
+            if (prevChild) {
+              prevChild.hasTrailingSpaces = true;
+            }
+            child.hasLeadingSpaces = true;
           }
-
-          if (text) {
-            localChildren.push({
-              type: "text",
-              value: text,
-              sourceSpan: new ParseSourceSpan(
-                child.sourceSpan.start.moveBy(leadingWhitespace.length),
-                child.sourceSpan.end.moveBy(-trailingWhitespace.length)
-              ),
-            });
-          }
-
           if (trailingWhitespace) {
-            localChildren.push(WHITESPACE_NODE);
+            child.hasTrailingSpaces = true;
+            if (nextChild) {
+              nextChild.hasLeadingSpaces = true;
+            }
           }
+        }
+      }
+    }
 
-          return localChildren;
-        })
-        // set hasLeadingSpaces/hasTrailingSpaces
-        .map((child, index, children) => {
-          if (child === WHITESPACE_NODE) {
-            return;
-          }
-
-          return {
-            ...child,
-            hasLeadingSpaces: children[index - 1] === WHITESPACE_NODE,
-            hasTrailingSpaces: children[index + 1] === WHITESPACE_NODE,
-          };
-        })
-        // filter whitespace nodes
-        .filter(Boolean)
-    );
     node.isWhitespaceSensitive = isWhitespaceSensitive;
     node.isIndentationSensitive = isIndentationSensitive;
   });
 }
 
 function addIsSelfClosing(ast /*, options */) {
-  ast.walk((node) =>
-    Object.assign(node, {
-      isSelfClosing:
-        !node.children ||
-        (node.type === "element" &&
-          (node.tagDefinition.isVoid ||
-            // self-closing
-            node.startSourceSpan === node.endSourceSpan)),
-    })
-  );
+  ast.walk((node) => {
+    node.isSelfClosing =
+      !node.children ||
+      (node.type === "element" &&
+        (node.tagDefinition.isVoid ||
+          // self-closing
+          node.startSourceSpan === node.endSourceSpan));
+  });
 }
 
 function addHasHtmComponentClosingTag(ast, options) {
-  ast.walk((node) =>
-    node.type !== "element"
-      ? node
-      : Object.assign(node, {
-          hasHtmComponentClosingTag:
-            node.endSourceSpan &&
-            /^<\s*\/\s*\/\s*>$/.test(
-              options.originalText.slice(
-                node.endSourceSpan.start.offset,
-                node.endSourceSpan.end.offset
-              )
-            ),
-        })
-  );
+  ast.walk((node) => {
+    if (node.type !== "element") {
+      return;
+    }
+
+    node.hasHtmComponentClosingTag =
+      node.endSourceSpan &&
+      /^<\s*\/\s*\/\s*>$/.test(
+        options.originalText.slice(
+          node.endSourceSpan.start.offset,
+          node.endSourceSpan.end.offset
+        )
+      );
+  });
 }
 
 function addCssDisplay(ast, options) {
-  ast.walk((node) =>
-    Object.assign(node, { cssDisplay: getNodeCssStyleDisplay(node, options) })
-  );
+  ast.walk((node) => {
+    node.cssDisplay = getNodeCssStyleDisplay(node, options);
+  });
 }
 
 /**
@@ -416,39 +374,37 @@ function addCssDisplay(ast, options) {
  */
 function addIsSpaceSensitive(ast, options) {
   ast.walk((node) => {
-    if (!node.children) {
+    const { children } = node;
+    if (!children) {
       return;
     }
-
-    if (node.children.length === 0) {
+    if (children.length === 0) {
       node.isDanglingSpaceSensitive = isDanglingSpaceSensitiveNode(node);
       return;
     }
-
-    node.setChildren(
-      node.children
-        .map((child) => ({
-          ...child,
-          isLeadingSpaceSensitive: isLeadingSpaceSensitiveNode(child, options),
-          isTrailingSpaceSensitive: isTrailingSpaceSensitiveNode(
-            child,
-            options
-          ),
-        }))
-        .map((child, index, children) => ({
-          ...child,
-          isLeadingSpaceSensitive:
-            index === 0
-              ? child.isLeadingSpaceSensitive
-              : children[index - 1].isTrailingSpaceSensitive &&
-                child.isLeadingSpaceSensitive,
-          isTrailingSpaceSensitive:
-            index === children.length - 1
-              ? child.isTrailingSpaceSensitive
-              : children[index + 1].isLeadingSpaceSensitive &&
-                child.isTrailingSpaceSensitive,
-        }))
-    );
+    for (const child of children) {
+      child.isLeadingSpaceSensitive = isLeadingSpaceSensitiveNode(
+        child,
+        options
+      );
+      child.isTrailingSpaceSensitive = isTrailingSpaceSensitiveNode(
+        child,
+        options
+      );
+    }
+    for (let index = 0; index < children.length; index++) {
+      const child = children[index];
+      child.isLeadingSpaceSensitive =
+        index === 0
+          ? child.isLeadingSpaceSensitive
+          : child.prev.isTrailingSpaceSensitive &&
+            child.isLeadingSpaceSensitive;
+      child.isTrailingSpaceSensitive =
+        index === children.length - 1
+          ? child.isTrailingSpaceSensitive
+          : child.next.isLeadingSpaceSensitive &&
+            child.isTrailingSpaceSensitive;
+    }
   });
 }
 
diff --git a/src/language-html/utils.js b/src/language-html/utils.js
index 5d9e822d9..4696285d5 100644
--- a/src/language-html/utils.js
+++ b/src/language-html/utils.js
@@ -113,12 +113,11 @@ function hasPrettierIgnore(node) {
     return false;
   }
 
-  if (typeof node.index !== "number" || node.index === 0) {
+  if (!node.prev) {
     return false;
   }
 
-  const prevNode = node.parent.children[node.index - 1];
-  return isPrettierIgnore(prevNode);
+  return isPrettierIgnore(node.prev);
 }
 
 function isPrettierIgnore(node) {
diff --git a/src/language-js/parse/postprocess/index.js b/src/language-js/parse/postprocess/index.js
index bf01da5eb..97c543a38 100644
--- a/src/language-js/parse/postprocess/index.js
+++ b/src/language-js/parse/postprocess/index.js
@@ -3,6 +3,7 @@
 const { getLast } = require("../../../common/util.js");
 const { locStart, locEnd } = require("../../loc.js");
 const { isTypeCastComment } = require("../../comments.js");
+const { isTsKeywordType } = require("../../utils.js");
 const visitNode = require("./visitNode.js");
 const { throwErrorForInvalidNodes } = require("./typescript.js");
 
@@ -79,7 +80,14 @@ function postprocess(ast, options) {
       }
       // remove redundant TypeScript nodes
       case "TSParenthesizedType": {
-        node.typeAnnotation.range = [locStart(node), locEnd(node)];
+        if (
+          !(
+            isTsKeywordType(node.typeAnnotation) ||
+            node.typeAnnotation.type === "TSThisType"
+          )
+        ) {
+          node.typeAnnotation.range = [locStart(node), locEnd(node)];
+        }
         return node.typeAnnotation;
       }
       case "TSTypeParameter":
diff --git a/src/language-js/print/typescript.js b/src/language-js/print/typescript.js
index 9d5547775..693ffcd8a 100644
--- a/src/language-js/print/typescript.js
+++ b/src/language-js/print/typescript.js
@@ -20,6 +20,7 @@ const {
   shouldPrintComma,
   isCallExpression,
   isMemberExpression,
+  isTsKeywordType,
 } = require("../utils.js");
 const { locStart, locEnd } = require("../loc.js");
 
@@ -58,7 +59,7 @@ function printTypescript(path, options, print) {
     return;
   }
 
-  if (node.type.endsWith("Keyword")) {
+  if (isTsKeywordType(node)) {
     return node.type.slice(2, -7).toLowerCase();
   }
 
diff --git a/src/language-js/utils.js b/src/language-js/utils.js
index 693e52b80..ccb5f4add 100644
--- a/src/language-js/utils.js
+++ b/src/language-js/utils.js
@@ -1322,6 +1322,10 @@ const markerForIfWithoutBlockAndSameLineComment = Symbol(
   "ifWithoutBlockAndSameLineComment"
 );
 
+function isTsKeywordType({ type }) {
+  return type.startsWith("TS") && type.endsWith("Keyword");
+}
+
 module.exports = {
   getFunctionParameters,
   iterateFunctionParametersPath,
@@ -1387,4 +1391,5 @@ module.exports = {
   getComments,
   CommentCheckFlags,
   markerForIfWithoutBlockAndSameLineComment,
+  isTsKeywordType,
 };
diff --git a/src/main/comments.js b/src/main/comments.js
index 2562cf260..77d961586 100644
--- a/src/main/comments.js
+++ b/src/main/comments.js
@@ -55,7 +55,8 @@ function getSortedChildNodes(node, options, resultArray) {
             key !== "precedingNode" &&
             key !== "followingNode" &&
             key !== "tokens" &&
-            key !== "comments"
+            key !== "comments" &&
+            key !== "parent"
         )
         .map(([, value]) => value));
 
diff --git a/tests/format/typescript/keyword-types/__snapshots__/jsfmt.spec.js.snap b/tests/format/typescript/keyword-types/__snapshots__/jsfmt.spec.js.snap
new file mode 100644
index 000000000..8f2097f3b
--- /dev/null
+++ b/tests/format/typescript/keyword-types/__snapshots__/jsfmt.spec.js.snap
@@ -0,0 +1,125 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`conditional-types.ts format 1`] = `
+====================================options=====================================
+parsers: ["typescript"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+export type UnwrappedResultRow<T> = {
+    [P in keyof T]: (
+        T[P] extends Req<infer a> ? (
+            a
+        ) : (
+            T[P] extends Opt<infer b> ? (
+                b
+            ) : (
+                // TEST
+                never
+            )
+        )
+    );
+};
+
+=====================================output=====================================
+export type UnwrappedResultRow<T> = {
+  [P in keyof T]: T[P] extends Req<infer a>
+    ? a
+    : T[P] extends Opt<infer b>
+    ? b
+    : // TEST
+      never;
+};
+
+================================================================================
+`;
+
+exports[`keyword-types-with-parens-comments.ts format 1`] = `
+====================================options=====================================
+parsers: ["typescript"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+let foo: (
+    // comment
+    any
+);
+let foo: (
+    // comment
+    null
+);
+let foo: (
+    // comment
+    this
+);
+let foo: (
+    // comment
+    number
+);
+let foo: (
+    // comment
+    void
+);
+let foo: (
+    // comment
+    boolean
+);
+let foo: (
+    // comment
+    bigint
+);
+let foo: (
+    // comment
+    symbol
+);
+let foo: (
+    // comment
+    string
+);
+let foo: (
+    // comment
+    never
+);
+let foo: (
+    // comment
+    object
+);
+let foo: (
+    // comment
+    undefined
+);
+let foo: (
+    // comment
+    unknown
+);
+
+=====================================output=====================================
+let foo: // comment
+any;
+let foo: // comment
+null;
+let foo: // comment
+this;
+let foo: // comment
+number;
+let foo: // comment
+void;
+let foo: // comment
+boolean;
+let foo: // comment
+bigint;
+let foo: // comment
+symbol;
+let foo: // comment
+string;
+let foo: // comment
+never;
+let foo: // comment
+object;
+let foo: // comment
+undefined;
+let foo: // comment
+unknown;
+
+================================================================================
+`;
diff --git a/tests/format/typescript/keyword-types/conditional-types.ts b/tests/format/typescript/keyword-types/conditional-types.ts
new file mode 100644
index 000000000..96aef0495
--- /dev/null
+++ b/tests/format/typescript/keyword-types/conditional-types.ts
@@ -0,0 +1,14 @@
+export type UnwrappedResultRow<T> = {
+    [P in keyof T]: (
+        T[P] extends Req<infer a> ? (
+            a
+        ) : (
+            T[P] extends Opt<infer b> ? (
+                b
+            ) : (
+                // TEST
+                never
+            )
+        )
+    );
+};
diff --git a/tests/format/typescript/keyword-types/jsfmt.spec.js b/tests/format/typescript/keyword-types/jsfmt.spec.js
new file mode 100644
index 000000000..2ea3bb6eb
--- /dev/null
+++ b/tests/format/typescript/keyword-types/jsfmt.spec.js
@@ -0,0 +1 @@
+run_spec(__dirname, ["typescript"]);
diff --git a/tests/format/typescript/keyword-types/keyword-types-with-parens-comments.ts b/tests/format/typescript/keyword-types/keyword-types-with-parens-comments.ts
new file mode 100644
index 000000000..9587c0dbb
--- /dev/null
+++ b/tests/format/typescript/keyword-types/keyword-types-with-parens-comments.ts
@@ -0,0 +1,52 @@
+let foo: (
+    // comment
+    any
+);
+let foo: (
+    // comment
+    null
+);
+let foo: (
+    // comment
+    this
+);
+let foo: (
+    // comment
+    number
+);
+let foo: (
+    // comment
+    void
+);
+let foo: (
+    // comment
+    boolean
+);
+let foo: (
+    // comment
+    bigint
+);
+let foo: (
+    // comment
+    symbol
+);
+let foo: (
+    // comment
+    string
+);
+let foo: (
+    // comment
+    never
+);
+let foo: (
+    // comment
+    object
+);
+let foo: (
+    // comment
+    undefined
+);
+let foo: (
+    // comment
+    unknown
+);