diff --git a/.eslintrc.yml b/.eslintrc.yml
index 5279c7ef0..16808d630 100644
--- a/.eslintrc.yml
+++ b/.eslintrc.yml
@@ -14,7 +14,6 @@ settings:
   import/internal-regex: ^linguist-languages/
 rules:
   prettier-internal-rules/require-json-extensions: error
-  prettier-internal-rules/better-parent-property-check-in-needs-parens: error
   curly: error
   dot-notation: error
   eqeqeq:
@@ -100,3 +99,9 @@ overrides:
         - error
         - patterns:
             - ".."
+  - files: src/language-js/needs-parens.js
+    rules:
+      prettier-internal-rules/better-parent-property-check-in-needs-parens: error
+  - files: src/**/*.js
+    rules:
+      prettier-internal-rules/prefer-fast-path-each: error
diff --git a/scripts/tools/eslint-plugin-prettier-internal-rules/index.js b/scripts/tools/eslint-plugin-prettier-internal-rules/index.js
index da954fddf..f7627723d 100644
--- a/scripts/tools/eslint-plugin-prettier-internal-rules/index.js
+++ b/scripts/tools/eslint-plugin-prettier-internal-rules/index.js
@@ -2,7 +2,8 @@
 
 module.exports = {
   rules: {
-    "require-json-extensions": require("./require-json-extensions"),
     "better-parent-property-check-in-needs-parens": require("./better-parent-property-check-in-needs-parens"),
+    "prefer-fast-path-each": require("./prefer-fast-path-each"),
+    "require-json-extensions": require("./require-json-extensions"),
   },
 };
diff --git a/scripts/tools/eslint-plugin-prettier-internal-rules/prefer-fast-path-each.js b/scripts/tools/eslint-plugin-prettier-internal-rules/prefer-fast-path-each.js
new file mode 100644
index 000000000..f4d6ad97d
--- /dev/null
+++ b/scripts/tools/eslint-plugin-prettier-internal-rules/prefer-fast-path-each.js
@@ -0,0 +1,42 @@
+"use strict";
+
+const selector = [
+  "ExpressionStatement",
+  ">",
+  "CallExpression.expression",
+  "[optional=false]",
+  ">",
+  "MemberExpression.callee",
+  "[computed=false]",
+  "[optional=false]",
+  ">",
+  "Identifier.property",
+  '[name="map"]',
+].join("");
+
+const messageId = "prefer-fast-path-each";
+
+module.exports = {
+  meta: {
+    type: "suggestion",
+    docs: {
+      url:
+        "https://github.com/prettier/prettier/blob/master/scripts/eslint-plugin-prettier-internal-rules/require-json-extensions.js",
+    },
+    messages: {
+      [messageId]: "Prefer `FastPath#each()` over `FastPath#map()`.",
+    },
+    fixable: "code",
+  },
+  create(context) {
+    return {
+      [selector](node) {
+        context.report({
+          node,
+          messageId,
+          fix: (fixer) => fixer.replaceText(node, "each"),
+        });
+      },
+    };
+  },
+};
diff --git a/src/common/fast-path.js b/src/common/fast-path.js
index 61b5883d6..2b14c7ff2 100644
--- a/src/common/fast-path.js
+++ b/src/common/fast-path.js
@@ -93,9 +93,7 @@ class FastPath {
     for (let i = 0; i < value.length; ++i) {
       if (i in value) {
         stack.push(i, value[i]);
-        // If the callback needs to know the value of i, call
-        // path.getName(), assuming path is the parameter name.
-        callback(this);
+        callback(this, i);
         stack.length -= 2;
       }
     }
diff --git a/src/language-css/printer-postcss.js b/src/language-css/printer-postcss.js
index 79c09530c..c1f3c892b 100644
--- a/src/language-css/printer-postcss.js
+++ b/src/language-css/printer-postcss.js
@@ -987,8 +987,7 @@ function genericPrint(path, options, print) {
 function printNodeSequence(path, options, print) {
   const node = path.getValue();
   const parts = [];
-  let i = 0;
-  path.map((pathChild) => {
+  path.each((pathChild, i) => {
     const prevNode = node.nodes[i - 1];
     if (
       prevNode &&
@@ -1034,7 +1033,6 @@ function printNodeSequence(path, options, print) {
         }
       }
     }
-    i++;
   }, "nodes");
 
   return concat(parts);
diff --git a/src/language-graphql/printer-graphql.js b/src/language-graphql/printer-graphql.js
index 5320a063a..c008d7dc8 100644
--- a/src/language-graphql/printer-graphql.js
+++ b/src/language-graphql/printer-graphql.js
@@ -26,7 +26,7 @@ function genericPrint(path, options, print) {
   switch (n.kind) {
     case "Document": {
       const parts = [];
-      path.map((pathChild, index) => {
+      path.each((pathChild, index) => {
         parts.push(concat([pathChild.call(print)]));
         if (index !== n.definitions.length - 1) {
           parts.push(hardline);
diff --git a/src/language-js/printer-estree.js b/src/language-js/printer-estree.js
index 1a28d00b8..4b2118911 100644
--- a/src/language-js/printer-estree.js
+++ b/src/language-js/printer-estree.js
@@ -294,7 +294,7 @@ function printPathNoParens(path, options, print, args) {
       // Babel 6
       if (n.directives) {
         const directivesCount = n.directives.length;
-        path.map((childPath, index) => {
+        path.each((childPath, index) => {
           parts.push(print(childPath), semi, hardline);
           if (
             (index < directivesCount - 1 || hasContents) &&
@@ -3573,7 +3573,7 @@ function printStatementSequence(path, options, print) {
   const bodyNode = path.getNode();
   const isClass = bodyNode.type === "ClassBody";
 
-  path.map((stmtPath, i) => {
+  path.each((stmtPath, i) => {
     const stmt = stmtPath.getValue();
 
     // Just in case the AST has been modified to contain falsy
@@ -4455,8 +4455,7 @@ function printJSXChildren(
   const n = path.getValue();
   const children = [];
 
-  // using `map` instead of `each` because it provides `i`
-  path.map((childPath, i) => {
+  path.each((childPath, i) => {
     const child = childPath.getValue();
     if (isLiteral(child)) {
       const text = rawText(child);
diff --git a/src/language-markdown/printer-markdown.js b/src/language-markdown/printer-markdown.js
index c370b67a3..5b743215f 100644
--- a/src/language-markdown/printer-markdown.js
+++ b/src/language-markdown/printer-markdown.js
@@ -577,19 +577,16 @@ function printLine(path, value, options) {
 function printTable(path, options, print) {
   const hardlineWithoutBreakParent = hardline.parts[0];
   const node = path.getValue();
-  const contents = []; // { [rowIndex: number]: { [columnIndex: number]: string } }
 
-  path.map((rowPath) => {
-    const rowContents = [];
-
-    rowPath.map((cellPath) => {
-      rowContents.push(
-        printDocToString(cellPath.call(print), options).formatted
-      );
-    }, "children");
-
-    contents.push(rowContents);
-  }, "children");
+  // { [rowIndex: number]: { [columnIndex: number]: string } }
+  const contents = path.map(
+    (rowPath) =>
+      rowPath.map(
+        (cellPath) => printDocToString(cellPath.call(print), options).formatted,
+        "children"
+      ),
+    "children"
+  );
 
   // Get the width of each column
   const columnMaxWidths = contents.reduce(
@@ -762,7 +759,7 @@ function printChildren(path, options, print, events) {
 
   let lastChildNode;
 
-  path.map((childPath, index) => {
+  path.each((childPath, index) => {
     const childNode = childPath.getValue();
 
     const result = processor(childPath, index);