diff --git a/src/language-css/clean.js b/src/language-css/clean.js
index 91eca2214..500742594 100644
--- a/src/language-css/clean.js
+++ b/src/language-css/clean.js
@@ -3,19 +3,17 @@
 const { isFrontMatterNode } = require("../common/util");
 const getLast = require("../utils/get-last");
 
-function clean(ast, newObj, parent) {
-  [
-    "raw", // front-matter
-    "raws",
-    "sourceIndex",
-    "source",
-    "before",
-    "after",
-    "trailingComma",
-  ].forEach((name) => {
-    delete newObj[name];
-  });
+const ignoredProperties = new Set([
+  "raw", // front-matter
+  "raws",
+  "sourceIndex",
+  "source",
+  "before",
+  "after",
+  "trailingComma",
+]);
 
+function clean(ast, newObj, parent) {
   if (isFrontMatterNode(ast) && ast.lang === "yaml") {
     delete newObj.value;
   }
@@ -170,6 +168,8 @@ function clean(ast, newObj, parent) {
   }
 }
 
+clean.ignoredProperties = ignoredProperties;
+
 function cleanCSSStrings(value) {
   return value.replace(/'/g, '"').replace(/\\([^\dA-Fa-f])/g, "$1");
 }
diff --git a/src/language-graphql/printer-graphql.js b/src/language-graphql/printer-graphql.js
index c008d7dc8..2b6b2a048 100644
--- a/src/language-graphql/printer-graphql.js
+++ b/src/language-graphql/printer-graphql.js
@@ -677,10 +677,8 @@ function printInterfaces(path, options, print) {
   return parts;
 }
 
-function clean(node, newNode /*, parent*/) {
-  delete newNode.loc;
-  delete newNode.comments;
-}
+function clean(/*node, newNode , parent*/) {}
+clean.ignoredProperties = new Set(["loc", "comments"]);
 
 module.exports = {
   print: genericPrint,
diff --git a/src/language-handlebars/clean.js b/src/language-handlebars/clean.js
index 9abcac2d2..db7b843ff 100644
--- a/src/language-handlebars/clean.js
+++ b/src/language-handlebars/clean.js
@@ -1,9 +1,6 @@
 "use strict";
 
-module.exports = function (ast, newNode) {
-  delete newNode.loc;
-  delete newNode.selfClosing;
-
+function clean(ast, newNode /*, parent*/) {
   // (Glimmer/HTML) ignore TextNode whitespace
   if (ast.type === "TextNode") {
     const trimmed = ast.chars.trim();
@@ -12,4 +9,7 @@ module.exports = function (ast, newNode) {
     }
     newNode.chars = trimmed;
   }
-};
+}
+clean.ignoredProperties = new Set(["loc", "selfClosing"]);
+
+module.exports = clean;
diff --git a/src/language-html/clean.js b/src/language-html/clean.js
index ee0c9bc05..4c9089cc9 100644
--- a/src/language-html/clean.js
+++ b/src/language-html/clean.js
@@ -2,13 +2,15 @@
 
 const { isFrontMatterNode } = require("../common/util");
 
-module.exports = function (ast, newNode) {
-  delete newNode.sourceSpan;
-  delete newNode.startSourceSpan;
-  delete newNode.endSourceSpan;
-  delete newNode.nameSpan;
-  delete newNode.valueSpan;
+const ignoredProperties = new Set([
+  "sourceSpan",
+  "startSourceSpan",
+  "endSourceSpan",
+  "nameSpan",
+  "valueSpan",
+]);
 
+function clean(ast, newNode) {
   if (ast.type === "text" || ast.type === "comment") {
     return null;
   }
@@ -25,4 +27,8 @@ module.exports = function (ast, newNode) {
   if (ast.type === "docType") {
     delete newNode.value;
   }
-};
+}
+
+clean.ignoredProperties = ignoredProperties;
+
+module.exports = clean;
diff --git a/src/language-js/printer-estree-json.js b/src/language-js/printer-estree-json.js
index 71f81ebdc..63af2bd25 100644
--- a/src/language-js/printer-estree-json.js
+++ b/src/language-js/printer-estree-json.js
@@ -58,23 +58,28 @@ function genericPrint(path, options, print) {
   }
 }
 
-function clean(node, newNode /*, parent*/) {
-  delete newNode.start;
-  delete newNode.end;
-  delete newNode.extra;
-  delete newNode.loc;
-  delete newNode.comments;
-  delete newNode.errors;
-  delete newNode.range;
+const ignoredProperties = new Set([
+  "start",
+  "end",
+  "extra",
+  "loc",
+  "comments",
+  "errors",
+  "range",
+]);
 
-  if (node.type === "Identifier") {
+function clean(node, newNode /*, parent*/) {
+  const { type } = node;
+  if (type === "Identifier") {
     return { type: "StringLiteral", value: node.name };
   }
-  if (node.type === "UnaryExpression" && node.operator === "+") {
+  if (type === "UnaryExpression" && node.operator === "+") {
     return newNode.argument;
   }
 }
 
+clean.ignoredProperties = ignoredProperties;
+
 module.exports = {
   preprocess,
   print: genericPrint,
diff --git a/src/language-markdown/clean.js b/src/language-markdown/clean.js
new file mode 100644
index 000000000..869eef9dd
--- /dev/null
+++ b/src/language-markdown/clean.js
@@ -0,0 +1,77 @@
+"use strict";
+
+const { isFrontMatterNode } = require("../common/util");
+const { startWithPragma } = require("./pragma");
+
+const ignoredProperties = new Set([
+  "position",
+  "raw", // front-matter
+]);
+function clean(ast, newObj, parent) {
+  // for codeblock
+  if (
+    ast.type === "front-matter" ||
+    ast.type === "code" ||
+    ast.type === "yaml" ||
+    ast.type === "import" ||
+    ast.type === "export" ||
+    ast.type === "jsx"
+  ) {
+    delete newObj.value;
+  }
+
+  if (ast.type === "list") {
+    delete newObj.isAligned;
+  }
+
+  if (ast.type === "list" || ast.type === "listItem") {
+    delete newObj.spread;
+    delete newObj.loose;
+  }
+
+  // texts can be splitted or merged
+  if (ast.type === "text") {
+    return null;
+  }
+
+  if (ast.type === "inlineCode") {
+    newObj.value = ast.value.replace(/[\t\n ]+/g, " ");
+  }
+
+  if (ast.type === "wikiLink") {
+    newObj.value = ast.value.trim().replace(/[\t\n]+/g, " ");
+  }
+
+  if (ast.type === "definition" || ast.type === "linkReference") {
+    newObj.label = ast.label
+      .trim()
+      .replace(/[\t\n ]+/g, " ")
+      .toLowerCase();
+  }
+
+  if (
+    (ast.type === "definition" ||
+      ast.type === "link" ||
+      ast.type === "image") &&
+    ast.title
+  ) {
+    newObj.title = ast.title.replace(/\\(["')])/g, "$1");
+  }
+
+  // for insert pragma
+  if (
+    parent &&
+    parent.type === "root" &&
+    parent.children.length > 0 &&
+    (parent.children[0] === ast ||
+      (isFrontMatterNode(parent.children[0]) && parent.children[1] === ast)) &&
+    ast.type === "html" &&
+    startWithPragma(ast.value)
+  ) {
+    return null;
+  }
+}
+
+clean.ignoredProperties = ignoredProperties;
+
+module.exports = clean;
diff --git a/src/language-markdown/printer-markdown.js b/src/language-markdown/printer-markdown.js
index 5b743215f..ca916505a 100644
--- a/src/language-markdown/printer-markdown.js
+++ b/src/language-markdown/printer-markdown.js
@@ -25,10 +25,11 @@ const {
   utils: { normalizeDoc },
   printer: { printDocToString },
 } = require("../document");
-const { replaceEndOfLineWith, isFrontMatterNode } = require("../common/util");
+const { replaceEndOfLineWith } = require("../common/util");
 const embed = require("./embed");
-const pragma = require("./pragma");
+const { insertPragma } = require("./pragma");
 const preprocess = require("./preprocess");
+const clean = require("./clean");
 const {
   getFencedCodeBlockValue,
   hasGitDiffFriendlyOrderedList,
@@ -935,74 +936,6 @@ function clamp(value, min, max) {
   return value < min ? min : value > max ? max : value;
 }
 
-function clean(ast, newObj, parent) {
-  delete newObj.position;
-  delete newObj.raw; // front-matter
-
-  // for codeblock
-  if (
-    ast.type === "front-matter" ||
-    ast.type === "code" ||
-    ast.type === "yaml" ||
-    ast.type === "import" ||
-    ast.type === "export" ||
-    ast.type === "jsx"
-  ) {
-    delete newObj.value;
-  }
-
-  if (ast.type === "list") {
-    delete newObj.isAligned;
-  }
-
-  if (ast.type === "list" || ast.type === "listItem") {
-    delete newObj.spread;
-    delete newObj.loose;
-  }
-
-  // texts can be splitted or merged
-  if (ast.type === "text") {
-    return null;
-  }
-
-  if (ast.type === "inlineCode") {
-    newObj.value = ast.value.replace(/[\t\n ]+/g, " ");
-  }
-
-  if (ast.type === "wikiLink") {
-    newObj.value = ast.value.trim().replace(/[\t\n]+/g, " ");
-  }
-
-  if (ast.type === "definition" || ast.type === "linkReference") {
-    newObj.label = ast.label
-      .trim()
-      .replace(/[\t\n ]+/g, " ")
-      .toLowerCase();
-  }
-
-  if (
-    (ast.type === "definition" ||
-      ast.type === "link" ||
-      ast.type === "image") &&
-    ast.title
-  ) {
-    newObj.title = ast.title.replace(/\\(["')])/g, "$1");
-  }
-
-  // for insert pragma
-  if (
-    parent &&
-    parent.type === "root" &&
-    parent.children.length > 0 &&
-    (parent.children[0] === ast ||
-      (isFrontMatterNode(parent.children[0]) && parent.children[1] === ast)) &&
-    ast.type === "html" &&
-    pragma.startWithPragma(ast.value)
-  ) {
-    return null;
-  }
-}
-
 function hasPrettierIgnore(path) {
   const index = +path.getName();
 
@@ -1020,5 +953,5 @@ module.exports = {
   embed,
   massageAstNode: clean,
   hasPrettierIgnore,
-  insertPragma: pragma.insertPragma,
+  insertPragma,
 };