diff --git a/src/babel/api/register/node.js b/src/babel/api/register/node.js
index 1878f5542d..ff73da2b79 100644
--- a/src/babel/api/register/node.js
+++ b/src/babel/api/register/node.js
@@ -12,7 +12,7 @@ var util             = require("../../util");
 var fs               = require("fs");
 
 sourceMapSupport.install({
-  retrieveSourceMap: function (source) {
+  retrieveSourceMap(source) {
     var map = maps && maps[source];
     if (map) {
       return {
diff --git a/src/babel/detection/index.js b/src/babel/detection/index.js
index 7d2eb54c86..0cee6e5624 100644
--- a/src/babel/detection/index.js
+++ b/src/babel/detection/index.js
@@ -15,7 +15,7 @@ function detect(ast) {
   };
 
   traverse(ast, {
-    enter: function (node, parent) {
+    enter(node, parent) {
       if (SYNTAX_KEYS[node.type]) {
         detectedSyntax(SYNTAX_KEYS[node.type]);
       }
diff --git a/src/babel/generation/generators/statements.js b/src/babel/generation/generators/statements.js
index f027f35826..41538c50a9 100644
--- a/src/babel/generation/generators/statements.js
+++ b/src/babel/generation/generators/statements.js
@@ -151,7 +151,7 @@ exports.SwitchStatement = function (node, print) {
 
   print.sequence(node.cases, {
     indent: true,
-    addNewlines: function (leading, cas) {
+    addNewlines(leading, cas) {
       if (!leading && node.cases[node.cases.length - 1] === cas) return -1;
     }
   });
diff --git a/src/babel/generation/node/whitespace.js b/src/babel/generation/node/whitespace.js
index 7b2bc55c0a..48655078af 100644
--- a/src/babel/generation/node/whitespace.js
+++ b/src/babel/generation/node/whitespace.js
@@ -46,7 +46,7 @@ var isType = function (node) {
 };
 
 exports.nodes = {
-  AssignmentExpression: function (node) {
+  AssignmentExpression(node) {
     var state = crawl(node.right);
     if ((state.hasCall && state.hasHelper) || state.hasFunction) {
       return {
@@ -56,13 +56,13 @@ exports.nodes = {
     }
   },
 
-  SwitchCase: function (node, parent) {
+  SwitchCase(node, parent) {
     return {
       before: node.consequent.length || parent.cases[0] === node
     };
   },
 
-  LogicalExpression: function (node) {
+  LogicalExpression(node) {
     if (t.isFunction(node.left) || t.isFunction(node.right)) {
       return {
         after: true
@@ -70,7 +70,7 @@ exports.nodes = {
     }
   },
 
-  Literal: function (node) {
+  Literal(node) {
     if (node.value === "use strict") {
       return {
         after: true
@@ -78,7 +78,7 @@ exports.nodes = {
     }
   },
 
-  CallExpression: function (node) {
+  CallExpression(node) {
     if (t.isFunction(node.callee) || isHelper(node)) {
       return {
         before: true,
@@ -87,7 +87,7 @@ exports.nodes = {
     }
   },
 
-  VariableDeclaration: function (node) {
+  VariableDeclaration(node) {
     for (var i = 0; i < node.declarations.length; i++) {
       var declar = node.declarations[i];
 
@@ -106,7 +106,7 @@ exports.nodes = {
     }
   },
 
-  IfStatement: function (node) {
+  IfStatement(node) {
     if (t.isBlockStatement(node.consequent)) {
       return {
         before: true,
@@ -126,15 +126,15 @@ exports.nodes.SpreadProperty = function (node, parent) {
 };
 
 exports.list = {
-  VariableDeclaration: function (node) {
+  VariableDeclaration(node) {
     return map(node.declarations, "init");
   },
 
-  ArrayExpression: function (node) {
+  ArrayExpression(node) {
     return node.elements;
   },
 
-  ObjectExpression: function (node) {
+  ObjectExpression(node) {
     return node.properties;
   }
 };
diff --git a/src/babel/helpers/code-frame.js b/src/babel/helpers/code-frame.js
index b123efb6fd..a1d3b5ae9c 100644
--- a/src/babel/helpers/code-frame.js
+++ b/src/babel/helpers/code-frame.js
@@ -77,7 +77,7 @@ module.exports = function (lines, lineNumber, colNumber) {
     start: start + 1,
     before: "  ",
     after: " | ",
-    transform: function (params) {
+    transform(params) {
       if (params.number !== lineNumber) {
         return;
       }
diff --git a/src/babel/transformation/file.js b/src/babel/transformation/file.js
index a458692585..760a682dca 100644
--- a/src/babel/transformation/file.js
+++ b/src/babel/transformation/file.js
@@ -417,7 +417,7 @@ File.prototype.call = function (key) {
 };
 
 var checkTransformerVisitor = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     checkNode(state.stack, node, scope);
   }
 };
diff --git a/src/babel/transformation/helpers/build-react-transformer.js b/src/babel/transformation/helpers/build-react-transformer.js
index 3e4c5a172a..5a867e9647 100644
--- a/src/babel/transformation/helpers/build-react-transformer.js
+++ b/src/babel/transformation/helpers/build-react-transformer.js
@@ -33,7 +33,7 @@ module.exports = function (exports, opts) {
   };
 
   exports.JSXMemberExpression = {
-    exit: function (node) {
+    exit(node) {
       node.computed = t.isLiteral(node.property);
       node.type = "MemberExpression";
     }
@@ -44,21 +44,21 @@ module.exports = function (exports, opts) {
   };
 
   exports.JSXAttribute = {
-    enter: function (node) {
+    enter(node) {
       var value = node.value;
       if (t.isLiteral(value) && isString(value.value)) {
         value.value = value.value.replace(/\n\s+/g, " ");
       }
     },
 
-    exit: function (node) {
+    exit(node) {
       var value = node.value || t.literal(true);
       return t.inherits(t.property("init", node.name, value), node);
     }
   };
 
   exports.JSXOpeningElement = {
-    exit: function (node, parent, scope, file) {
+    exit(node, parent, scope, file) {
       var tagExpr = node.name;
       var args = [];
 
@@ -146,7 +146,7 @@ module.exports = function (exports, opts) {
   };
 
   exports.JSXElement = {
-    exit: function (node) {
+    exit(node) {
       var callExpr = node.openingElement;
 
       for (var i = 0; i < node.children.length; i++) {
diff --git a/src/babel/transformation/helpers/name-method.js b/src/babel/transformation/helpers/name-method.js
index cd2d9afe66..73a4cb42b0 100644
--- a/src/babel/transformation/helpers/name-method.js
+++ b/src/babel/transformation/helpers/name-method.js
@@ -4,7 +4,7 @@ var util = require("../../util");
 var t    = require("../../types");
 
 var visitor = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     // check if this node is a referenced identifier that matches the same as our
     // function id
     if (!t.isReferencedIdentifier(node, parent, { name: state.name })) return;
@@ -99,7 +99,7 @@ exports.bare = function (node, parent, scope) {
 
   var id;
   if (t.isProperty(parent) && parent.kind === "init" && !parent.computed) {
-    // { foo: function () {} };
+    // { foo() {} };
     id = parent.key;
   } else if (t.isVariableDeclarator(parent)) {
     // var foo = function () {};
diff --git a/src/babel/transformation/helpers/remap-async-to-generator.js b/src/babel/transformation/helpers/remap-async-to-generator.js
index fd5aacac31..da9b68209b 100644
--- a/src/babel/transformation/helpers/remap-async-to-generator.js
+++ b/src/babel/transformation/helpers/remap-async-to-generator.js
@@ -3,7 +3,7 @@
 var t = require("../../types");
 
 var visitor = {
-  enter: function (node) {
+  enter(node) {
     if (t.isFunction(node)) this.skip();
 
     if (t.isAwaitExpression(node)) {
diff --git a/src/babel/transformation/helpers/replace-supers.js b/src/babel/transformation/helpers/replace-supers.js
index f61be9b5a2..dc9723a151 100644
--- a/src/babel/transformation/helpers/replace-supers.js
+++ b/src/babel/transformation/helpers/replace-supers.js
@@ -96,7 +96,7 @@ ReplaceSupers.prototype.replace = function () {
 };
 
 var visitor = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     var topLevel = state.topLevel;
     var self = state.self;
 
diff --git a/src/babel/transformation/modules/_default.js b/src/babel/transformation/modules/_default.js
index 5fdd180199..a17f8ae159 100644
--- a/src/babel/transformation/modules/_default.js
+++ b/src/babel/transformation/modules/_default.js
@@ -40,7 +40,7 @@ DefaultFormatter.prototype.bumpImportOccurences = function (node) {
 };
 
 var exportsVisitor = {
-  enter: function (node, parent, scope, formatter) {
+  enter(node, parent, scope, formatter) {
     var declar = node && node.declaration;
     if (t.isExportDeclaration(node)) {
       formatter.hasLocalImports = true;
@@ -65,7 +65,7 @@ DefaultFormatter.prototype.getLocalExports = function () {
 };
 
 var importsVisitor = {
-  enter: function (node, parent, scope, formatter) {
+  enter(node, parent, scope, formatter) {
     if (t.isImportDeclaration(node)) {
       formatter.hasLocalImports = true;
       extend(formatter.localImports, t.getBindingIdentifiers(node));
@@ -79,7 +79,7 @@ DefaultFormatter.prototype.getLocalImports = function () {
 };
 
 var remapVisitor = {
-  enter: function (node, parent, scope, formatter) {
+  enter(node, parent, scope, formatter) {
     if (t.isUpdateExpression(node) && formatter.isLocalReference(node.argument, scope)) {
       this.skip();
 
diff --git a/src/babel/transformation/modules/system.js b/src/babel/transformation/modules/system.js
index 38ceec3799..dc438cf290 100644
--- a/src/babel/transformation/modules/system.js
+++ b/src/babel/transformation/modules/system.js
@@ -68,7 +68,7 @@ SystemFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
 };
 
 var runnerSettersVisitor = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     if (node._importSource === state.source) {
       if (t.isVariableDeclaration(node)) {
         each(node.declarations, function (declar) {
@@ -103,7 +103,7 @@ SystemFormatter.prototype.buildRunnerSetters = function (block, hoistDeclarators
 };
 
 var hoistVariablesVisitor = {
-  enter: function (node, parent, scope, hoistDeclarators) {
+  enter(node, parent, scope, hoistDeclarators) {
     if (t.isFunction(node)) {
       // nothing inside is accessible
       return this.skip();
@@ -148,7 +148,7 @@ var hoistVariablesVisitor = {
 };
 
 var hoistFunctionsVisitor = {
-  enter: function (node, parent, scope, handlerBody) {
+  enter(node, parent, scope, handlerBody) {
     if (t.isFunction(node)) this.skip();
 
     if (t.isFunctionDeclaration(node) || node._blockHoist) {
diff --git a/src/babel/transformation/transformers/es6/block-scoping-tdz.js b/src/babel/transformation/transformers/es6/block-scoping-tdz.js
index 8b765b7d9a..0e6e62e8f1 100644
--- a/src/babel/transformation/transformers/es6/block-scoping-tdz.js
+++ b/src/babel/transformation/transformers/es6/block-scoping-tdz.js
@@ -3,7 +3,7 @@
 var t = require("../../../types");
 
 var visitor = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     if (!t.isReferencedIdentifier(node, parent)) return;
 
     var declared = state.letRefs[node.name];
diff --git a/src/babel/transformation/transformers/es6/block-scoping.js b/src/babel/transformation/transformers/es6/block-scoping.js
index 984e5585f3..b26988de3e 100644
--- a/src/babel/transformation/transformers/es6/block-scoping.js
+++ b/src/babel/transformation/transformers/es6/block-scoping.js
@@ -266,7 +266,7 @@ BlockScoping.prototype.wrapClosure = function () {
 };
 
 var letReferenceFunctionVisitor = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     // not a direct reference
     if (!t.isReferencedIdentifier(node, parent)) return;
 
@@ -282,7 +282,7 @@ var letReferenceFunctionVisitor = {
 };
 
 var letReferenceBlockVisitor = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     if (t.isFunction(node)) {
       scope.traverse(node, letReferenceFunctionVisitor, state);
       return this.skip();
@@ -351,7 +351,7 @@ var loopNodeTo = function (node) {
 };
 
 var loopVisitor = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     var replace;
 
     if (t.isLoop(node)) {
@@ -403,7 +403,7 @@ var loopVisitor = {
 };
 
 var loopLabelVisitor = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     if (t.isLabeledStatement(node)) {
       state.innerLabels.push(node.label.name);
     }
@@ -436,7 +436,7 @@ BlockScoping.prototype.checkLoop = function () {
 };
 
 var hoistVarDeclarationsVisitor = {
-  enter: function (node, parent, scope, self) {
+  enter(node, parent, scope, self) {
     if (t.isForStatement(node)) {
       if (isVar(node.init, node)) {
         node.init = t.sequenceExpression(self.pushDeclar(node.init));
diff --git a/src/babel/transformation/transformers/es6/constants.js b/src/babel/transformation/transformers/es6/constants.js
index a58cd16256..5b5a0ce87b 100644
--- a/src/babel/transformation/transformers/es6/constants.js
+++ b/src/babel/transformation/transformers/es6/constants.js
@@ -8,7 +8,7 @@ exports.check = function (node) {
 };
 
 var visitor = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     if (t.isAssignmentExpression(node) || t.isUpdateExpression(node)) {
       var ids = t.getBindingIdentifiers(node);
 
diff --git a/src/babel/transformation/transformers/es6/for-of.js b/src/babel/transformation/transformers/es6/for-of.js
index 929cef330d..7428ca4fb3 100644
--- a/src/babel/transformation/transformers/es6/for-of.js
+++ b/src/babel/transformation/transformers/es6/for-of.js
@@ -38,7 +38,7 @@ exports.ForOfStatement = function (node, parent, scope, file) {
 };
 
 var breakVisitor = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     if (t.isLoop(node)) {
       state.ignoreLabeless = true;
       scope.traverse(node, breakVisitor, state);
diff --git a/src/babel/transformation/transformers/es6/parameters.default.js b/src/babel/transformation/transformers/es6/parameters.default.js
index 7736d63f89..f755f256aa 100644
--- a/src/babel/transformation/transformers/es6/parameters.default.js
+++ b/src/babel/transformation/transformers/es6/parameters.default.js
@@ -15,7 +15,7 @@ var hasDefaults = function (node) {
 };
 
 var iifeVisitor = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     if (!t.isReferencedIdentifier(node, parent)) return;
     if (!state.scope.hasOwnBinding(node.name)) return;
     if (state.scope.bindingIdentifierEquals(node.name, node)) return;
diff --git a/src/babel/transformation/transformers/es6/tail-call.js b/src/babel/transformation/transformers/es6/tail-call.js
index 17e41d68a7..0a8142599e 100644
--- a/src/babel/transformation/transformers/es6/tail-call.js
+++ b/src/babel/transformation/transformers/es6/tail-call.js
@@ -305,7 +305,7 @@ TailCallTransformer.prototype.subTransformCallExpression = function (node) {
 
 // looks for and replaces tail recursion calls
 var firstPass = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     if (t.isIfStatement(node)) {
       if (t.isReturnStatement(node.alternate)) {
         t.ensureBlock(node, "alternate");
@@ -335,7 +335,7 @@ var firstPass = {
 // hoists up function declarations, replaces `this` and `arguments` and marks
 // them as needed
 var secondPass = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     if (t.isThisExpression(node)) {
       state.needsThis = true;
       return state.getThisId();
@@ -357,7 +357,7 @@ var secondPass = {
 
 // optimizes recursion by removing `this` and `arguments` if they aren't used
 var thirdPass = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     if (!t.isExpressionStatement(node)) return;
 
     var expr = node.expression;
diff --git a/src/babel/transformation/transformers/es7/exponentiation-operator.js b/src/babel/transformation/transformers/es7/exponentiation-operator.js
index 3bc8071af3..d0699e6348 100644
--- a/src/babel/transformation/transformers/es7/exponentiation-operator.js
+++ b/src/babel/transformation/transformers/es7/exponentiation-operator.js
@@ -12,7 +12,7 @@ var MATH_POW = t.memberExpression(t.identifier("Math"), t.identifier("pow"));
 build(exports, {
   operator: "**",
 
-  build: function (left, right) {
+  build(left, right) {
     return t.callExpression(MATH_POW, [left, right]);
   }
 });
diff --git a/src/babel/transformation/transformers/internal/alias-functions.js b/src/babel/transformation/transformers/internal/alias-functions.js
index 10f16d49d7..743347b539 100644
--- a/src/babel/transformation/transformers/internal/alias-functions.js
+++ b/src/babel/transformation/transformers/internal/alias-functions.js
@@ -3,7 +3,7 @@
 var t = require("../../../types");
 
 var functionChildrenVisitor = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     if (t.isFunction(node) && !node._aliasFunction) {
       return this.skip();
     }
@@ -25,7 +25,7 @@ var functionChildrenVisitor = {
 };
 
 var functionVisitor = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     if (!node._aliasFunction) {
       if (t.isFunction(node)) {
         // stop traversal of this node as it'll be hit again by this transformer
@@ -47,10 +47,10 @@ var go = function (getBody, node, scope) {
   var thisId;
 
   var state = {
-    getArgumentsId: function () {
+    getArgumentsId() {
       return argumentsId = argumentsId || scope.generateUidIdentifier("arguments");
     },
-    getThisId: function () {
+    getThisId() {
       return thisId = thisId || scope.generateUidIdentifier("this");
     }
   };
diff --git a/src/babel/transformation/transformers/internal/block-hoist.js b/src/babel/transformation/transformers/internal/block-hoist.js
index 95d13967d7..565ebb3f20 100644
--- a/src/babel/transformation/transformers/internal/block-hoist.js
+++ b/src/babel/transformation/transformers/internal/block-hoist.js
@@ -13,7 +13,7 @@ var values  = require("lodash/object/values");
 
 exports.BlockStatement =
 exports.Program = {
-  exit: function (node) {
+  exit(node) {
     var hasChange = false;
     for (var i = 0; i < node.body.length; i++) {
       var bodyNode = node.body[i];
diff --git a/src/babel/transformation/transformers/minification/dead-code-elimination.js b/src/babel/transformation/transformers/minification/dead-code-elimination.js
index f1f1a45fe6..cc8dc40ca5 100644
--- a/src/babel/transformation/transformers/minification/dead-code-elimination.js
+++ b/src/babel/transformation/transformers/minification/dead-code-elimination.js
@@ -17,7 +17,7 @@ exports.ExpressionStatement = function (node) {
 };
 
 exports.IfStatement = {
-  exit: function (node) {
+  exit(node) {
     // todo: in scenarios where we can just return the consequent or
     // alternate we should drop the block statement if it contains no
     // block scoped variables
diff --git a/src/babel/transformation/transformers/other/react-compat.js b/src/babel/transformation/transformers/other/react-compat.js
index b8771eae35..48a67231bb 100644
--- a/src/babel/transformation/transformers/other/react-compat.js
+++ b/src/babel/transformation/transformers/other/react-compat.js
@@ -10,11 +10,11 @@ exports.manipulateOptions = function (opts) {
 exports.optional = true;
 
 require("../../helpers/build-react-transformer")(exports, {
-  pre: function (state) {
+  pre(state) {
     state.callee = state.tagExpr;
   },
 
-  post: function (state) {
+  post(state) {
     if (react.isCompatTag(state.tagName)) {
       state.call = t.callExpression(
         t.memberExpression(
diff --git a/src/babel/transformation/transformers/other/react.js b/src/babel/transformation/transformers/other/react.js
index 047490c635..30bc8d3284 100644
--- a/src/babel/transformation/transformers/other/react.js
+++ b/src/babel/transformation/transformers/other/react.js
@@ -27,7 +27,7 @@ exports.Program = function (node, parent, scope, file) {
 };
 
 require("../../helpers/build-react-transformer")(exports, {
-  pre: function (state) {
+  pre(state) {
     var tagName = state.tagName;
     var args    = state.args;
     if (react.isCompatTag(tagName)) {
@@ -37,7 +37,7 @@ require("../../helpers/build-react-transformer")(exports, {
     }
   },
 
-  post: function (state, file) {
+  post(state, file) {
     state.callee = file.get("jsxIdentifier");
   }
 });
diff --git a/src/babel/transformation/transformers/other/regenerator.js b/src/babel/transformation/transformers/other/regenerator.js
index 8ebb56e701..468f39c99b 100644
--- a/src/babel/transformation/transformers/other/regenerator.js
+++ b/src/babel/transformation/transformers/other/regenerator.js
@@ -8,7 +8,7 @@ exports.check = function (node) {
 };
 
 exports.Program = {
-  enter: function (ast) {
+  enter(ast) {
     regenerator.transform(ast);
     this.stop();
   }
diff --git a/src/babel/transformation/transformers/other/runtime.js b/src/babel/transformation/transformers/other/runtime.js
index 6cb9f39421..dd7f0870b3 100644
--- a/src/babel/transformation/transformers/other/runtime.js
+++ b/src/babel/transformation/transformers/other/runtime.js
@@ -22,7 +22,7 @@ var ALIASABLE_CONSTRUCTORS = [
 ];
 
 var astVisitor = {
-  enter: function (node, parent, scope, file) {
+  enter(node, parent, scope, file) {
     var prop;
 
     if (t.isMemberExpression(node) && t.isReferenced(node, parent)) {
diff --git a/src/babel/transformation/transformers/playground/mallet-operator.js b/src/babel/transformation/transformers/playground/mallet-operator.js
index ff6aff5b6b..9b8cc62585 100644
--- a/src/babel/transformation/transformers/playground/mallet-operator.js
+++ b/src/babel/transformation/transformers/playground/mallet-operator.js
@@ -7,7 +7,7 @@ var t        = require("../../../types");
 exports.playground = true;
 
 build(exports, {
-  is: function (node, file) {
+  is(node, file) {
     var is = t.isAssignmentExpression(node) && node.operator === "||=";
     if (is) {
       var left = node.left;
@@ -18,7 +18,7 @@ build(exports, {
     }
   },
 
-  build: function (node) {
+  build(node) {
     return t.unaryExpression("!", node, true);
   }
 });
diff --git a/src/babel/transformation/transformers/playground/memoization-operator.js b/src/babel/transformation/transformers/playground/memoization-operator.js
index 4afe6f1b23..87c0fbc24e 100644
--- a/src/babel/transformation/transformers/playground/memoization-operator.js
+++ b/src/babel/transformation/transformers/playground/memoization-operator.js
@@ -6,13 +6,13 @@ var t     = require("../../../types");
 exports.playground = true;
 
 build(exports, {
-  is: function (node) {
+  is(node) {
     var is = t.isAssignmentExpression(node) && node.operator === "?=";
     if (is) t.assertMemberExpression(node.left);
     return is;
   },
 
-  build: function (node, file) {
+  build(node, file) {
     return t.unaryExpression(
       "!",
       t.callExpression(
diff --git a/src/babel/transformation/transformers/playground/object-getter-memoization.js b/src/babel/transformation/transformers/playground/object-getter-memoization.js
index 7ceaee2943..59a8e3db08 100644
--- a/src/babel/transformation/transformers/playground/object-getter-memoization.js
+++ b/src/babel/transformation/transformers/playground/object-getter-memoization.js
@@ -5,7 +5,7 @@ var t = require("../../../types");
 exports.playground = true;
 
 var visitor = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     if (t.isFunction(node)) return this.skip();
 
     if (t.isReturnStatement(node) && node.argument) {
diff --git a/src/babel/traversal/path.js b/src/babel/traversal/path.js
index de267cc604..4fef7c00f7 100644
--- a/src/babel/traversal/path.js
+++ b/src/babel/traversal/path.js
@@ -60,11 +60,11 @@ TraversalPath.prototype.flatten = function () {
 };
 
 Object.defineProperty(TraversalPath.prototype, "node", {
-  get: function () {
+  get() {
     return this.container[this.key];
   },
 
-  set: function (replacement) {
+  set(replacement) {
     var isArray = Array.isArray(replacement);
 
     // inherit comments from original node to the first replacement node
diff --git a/src/babel/traversal/scope.js b/src/babel/traversal/scope.js
index 8304a4f1ac..f83aea8e69 100644
--- a/src/babel/traversal/scope.js
+++ b/src/babel/traversal/scope.js
@@ -181,7 +181,7 @@ Scope.prototype.rename = function (oldName, newName) {
   var scope = info.scope;
 
   scope.traverse(scope.block, {
-    enter: function (node, parent, scope) {
+    enter(node, parent, scope) {
       if (t.isReferencedIdentifier(node, parent) && node.name === oldName) {
         node.name = newName;
       } else if (t.isDeclaration(node)) {
@@ -372,7 +372,7 @@ Scope.prototype.registerVariableDeclaration = function (declar) {
 };
 
 var functionVariableVisitor = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     if (t.isFor(node)) {
       each(t.FOR_INIT_KEYS, function (key) {
         var declar = node[key];
@@ -413,7 +413,7 @@ Scope.prototype.hasGlobal = function (name) {
 };
 
 var programReferenceVisitor = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     if (t.isReferencedIdentifier(node, parent) && !scope.hasBinding(node.name)) {
       state.addGlobal(node);
     } else if (t.isLabeledStatement(node)) {
@@ -425,7 +425,7 @@ var programReferenceVisitor = {
 };
 
 var blockVariableVisitor = {
-  enter: function (node, parent, scope, state) {
+  enter(node, parent, scope, state) {
     if (t.isFunctionDeclaration(node) || t.isBlockScoped(node)) {
       state.registerDeclaration(node);
     } else if (t.isScope(node, parent)) {
diff --git a/src/babel/util.js b/src/babel/util.js
index 2b0b935838..10e1f98cf3 100644
--- a/src/babel/util.js
+++ b/src/babel/util.js
@@ -65,7 +65,7 @@ exports.booleanify = function (val) {
 };
 
 var templateVisitor = {
-  enter: function (node, parent, scope, nodes) {
+  enter(node, parent, scope, nodes) {
     if (t.isExpressionStatement(node)) {
       node = node.expression;
     }