Remove vars

packages/react-dom/index.fb.js

@@ -7,7 +7,7 @@
 
 'use strict';
 
-var ReactDOMFB = require('./src/client/ReactDOMFB');
+const ReactDOMFB = require('./src/client/ReactDOMFB');
 
 // TODO: decide on the top-level export form.
 // This is hacky but makes it work with both Rollup and Jest.

packages/react-dom/index.js

@@ -9,7 +9,7 @@
 
 'use strict';
 
-var ReactDOM = require('./src/client/ReactDOM');
+const ReactDOM = require('./src/client/ReactDOM');
 
 // TODO: decide on the top-level export form.
 // This is hacky but makes it work with both Rollup and Jest.

packages/react-dom/server.browser.js

@@ -9,7 +9,7 @@
 
 'use strict';
 
-var ReactDOMServer = require('./src/server/ReactDOMServerBrowser');
+const ReactDOMServer = require('./src/server/ReactDOMServerBrowser');
 
 // TODO: decide on the top-level export form.
 // This is hacky but makes it work with both Rollup and Jest

packages/react-dom/server.node.js

@@ -9,7 +9,7 @@
 
 'use strict';
 
-var ReactDOMServer = require('./src/server/ReactDOMServerNode');
+const ReactDOMServer = require('./src/server/ReactDOMServerNode');
 
 // TODO: decide on the top-level export form.
 // This is hacky but makes it work with both Rollup and Jest

packages/react-dom/src/__tests__/ReactDOM-test.js

@@ -18,9 +18,9 @@ describe('ReactDOM', () => {
   // supports real submit events.
   /*
   it('should bubble onSubmit', function() {
-    var count = 0;
-    var form;
-    var Parent = React.createClass({
+    const count = 0;
+    const form;
+    const Parent = React.createClass({
       handleSubmit: function() {
         count++;
         return false;
@@ -29,15 +29,15 @@ describe('ReactDOM', () => {
         return <Child />;
       }
     });
-    var Child = React.createClass({
+    const Child = React.createClass({
       render: function() {
         return <form><input type="submit" value="Submit" /></form>;
       },
       componentDidMount: function() {
         form = ReactDOM.findDOMNode(this);
       }
     });
-    var instance = ReactTestUtils.renderIntoDocument(<Parent />);
+    const instance = ReactTestUtils.renderIntoDocument(<Parent />);
     form.submit();
     expect(count).toEqual(1);
   });

packages/react-dom/src/__tests__/ReactDOMInput-test.js

@@ -258,8 +258,8 @@ describe('ReactDOMInput', () => {
       }
     }
 
-    var stub = ReactTestUtils.renderIntoDocument(<Stub />);
-    var node = ReactDOM.findDOMNode(stub);
+    const stub = ReactTestUtils.renderIntoDocument(<Stub />);
+    const node = ReactDOM.findDOMNode(stub);
     stub.setState({value: 0});
 
     expect(node.value).toEqual('0');
@@ -628,36 +628,36 @@ describe('ReactDOMInput', () => {
   });
 
   it('should properly transition a text input from 0 to an empty 0.0', function() {
-    var container = document.createElement('div');
+    const container = document.createElement('div');
 
     ReactDOM.render(<input type="text" value={0} />, container);
     ReactDOM.render(<input type="text" value="0.0" />, container);
 
-    var node = container.firstChild;
+    const node = container.firstChild;
 
     expect(node.value).toBe('0.0');
     expect(node.defaultValue).toBe('0.0');
   });
 
   it('should properly transition a number input from "" to 0', function() {
-    var container = document.createElement('div');
+    const container = document.createElement('div');
 
     ReactDOM.render(<input type="number" value="" />, container);
     ReactDOM.render(<input type="number" value={0} />, container);
 
-    var node = container.firstChild;
+    const node = container.firstChild;
 
     expect(node.value).toBe('0');
     expect(node.defaultValue).toBe('0');
   });
 
   it('should properly transition a number input from "" to "0"', function() {
-    var container = document.createElement('div');
+    const container = document.createElement('div');
 
     ReactDOM.render(<input type="number" value="" />, container);
     ReactDOM.render(<input type="number" value="0" />, container);
 
-    var node = container.firstChild;
+    const node = container.firstChild;
 
     expect(node.value).toBe('0');
     expect(node.defaultValue).toBe('0');
@@ -1644,12 +1644,12 @@ describe('ReactDOMInput', () => {
   describe('When given a Symbol value', function() {
     it('treats initial Symbol value as an empty string', function() {
       spyOnDev(console, 'error');
-      var container = document.createElement('div');
+      const container = document.createElement('div');
       ReactDOM.render(
         <input value={Symbol('foobar')} onChange={() => {}} />,
         container,
       );
-      var node = container.firstChild;
+      const node = container.firstChild;
 
       expect(node.value).toBe('');
       expect(node.getAttribute('value')).toBe('');
@@ -1664,13 +1664,13 @@ describe('ReactDOMInput', () => {
 
     it('treats updated Symbol value as an empty string', function() {
       spyOnDev(console, 'error');
-      var container = document.createElement('div');
+      const container = document.createElement('div');
       ReactDOM.render(<input value="foo" onChange={() => {}} />, container);
       ReactDOM.render(
         <input value={Symbol('foobar')} onChange={() => {}} />,
         container,
       );
-      var node = container.firstChild;
+      const node = container.firstChild;
 
       expect(node.value).toBe('');
       expect(node.getAttribute('value')).toBe('');
@@ -1684,20 +1684,20 @@ describe('ReactDOMInput', () => {
     });
 
     it('treats initial Symbol defaultValue as an empty string', function() {
-      var container = document.createElement('div');
+      const container = document.createElement('div');
       ReactDOM.render(<input defaultValue={Symbol('foobar')} />, container);
-      var node = container.firstChild;
+      const node = container.firstChild;
 
       expect(node.value).toBe('');
       expect(node.getAttribute('value')).toBe('');
       // TODO: we should warn here.
     });
 
     it('treats updated Symbol defaultValue as an empty string', function() {
-      var container = document.createElement('div');
+      const container = document.createElement('div');
       ReactDOM.render(<input defaultValue="foo" />, container);
       ReactDOM.render(<input defaultValue={Symbol('foobar')} />, container);
-      var node = container.firstChild;
+      const node = container.firstChild;
 
       expect(node.value).toBe('foo');
       expect(node.getAttribute('value')).toBe('');
@@ -1708,12 +1708,12 @@ describe('ReactDOMInput', () => {
   describe('When given a function value', function() {
     it('treats initial function value as an empty string', function() {
       spyOnDev(console, 'error');
-      var container = document.createElement('div');
+      const container = document.createElement('div');
       ReactDOM.render(
         <input value={() => {}} onChange={() => {}} />,
         container,
       );
-      var node = container.firstChild;
+      const node = container.firstChild;
 
       expect(node.value).toBe('');
       expect(node.getAttribute('value')).toBe('');
@@ -1728,13 +1728,13 @@ describe('ReactDOMInput', () => {
 
     it('treats updated function value as an empty string', function() {
       spyOnDev(console, 'error');
-      var container = document.createElement('div');
+      const container = document.createElement('div');
       ReactDOM.render(<input value="foo" onChange={() => {}} />, container);
       ReactDOM.render(
         <input value={() => {}} onChange={() => {}} />,
         container,
       );
-      var node = container.firstChild;
+      const node = container.firstChild;
 
       expect(node.value).toBe('');
       expect(node.getAttribute('value')).toBe('');
@@ -1748,20 +1748,20 @@ describe('ReactDOMInput', () => {
     });
 
     it('treats initial function defaultValue as an empty string', function() {
-      var container = document.createElement('div');
+      const container = document.createElement('div');
       ReactDOM.render(<input defaultValue={() => {}} />, container);
-      var node = container.firstChild;
+      const node = container.firstChild;
 
       expect(node.value).toBe('');
       expect(node.getAttribute('value')).toBe('');
       // TODO: we should warn here.
     });
 
     it('treats updated function defaultValue as an empty string', function() {
-      var container = document.createElement('div');
+      const container = document.createElement('div');
       ReactDOM.render(<input defaultValue="foo" />, container);
       ReactDOM.render(<input defaultValue={() => {}} />, container);
-      var node = container.firstChild;
+      const node = container.firstChild;
 
       expect(node.value).toBe('foo');
       expect(node.getAttribute('value')).toBe('');

packages/react-dom/src/client/DOMPropertyOperations.js

@@ -17,11 +17,11 @@ import warning from 'fbjs/lib/warning';
 
 // isAttributeNameSafe() is currently duplicated in DOMMarkupOperations.
 // TODO: Find a better place for this.
-var VALID_ATTRIBUTE_NAME_REGEX = new RegExp(
+const VALID_ATTRIBUTE_NAME_REGEX = new RegExp(
   '^[' + ATTRIBUTE_NAME_START_CHAR + '][' + ATTRIBUTE_NAME_CHAR + ']*$',
 );
-var illegalAttributeNameCache = {};
-var validatedAttributeNameCache = {};
+const illegalAttributeNameCache = {};
+const validatedAttributeNameCache = {};
 function isAttributeNameSafe(attributeName) {
   if (validatedAttributeNameCache.hasOwnProperty(attributeName)) {
     return true;
@@ -71,18 +71,18 @@ export function setAttributeForRoot(node) {
  */
 export function getValueForProperty(node, name, expected) {
   if (__DEV__) {
-    var propertyInfo = getPropertyInfo(name);
+    const propertyInfo = getPropertyInfo(name);
     if (propertyInfo) {
       if (propertyInfo.mustUseProperty) {
         return node[propertyInfo.propertyName];
       } else {
-        var attributeName = propertyInfo.attributeName;
+        const attributeName = propertyInfo.attributeName;
 
-        var stringValue = null;
+        let stringValue = null;
 
         if (propertyInfo.hasOverloadedBooleanValue) {
           if (node.hasAttribute(attributeName)) {
-            var value = node.getAttribute(attributeName);
+            const value = node.getAttribute(attributeName);
             if (value === '') {
               return true;
             }
@@ -137,7 +137,7 @@ export function getValueForAttribute(node, name, expected) {
     if (!node.hasAttribute(name)) {
       return expected === undefined ? undefined : null;
     }
-    var value = node.getAttribute(name);
+    const value = node.getAttribute(name);
     if (value === '' + expected) {
       return expected;
     }
@@ -153,7 +153,7 @@ export function getValueForAttribute(node, name, expected) {
  * @param {*} value
  */
 export function setValueForProperty(node, name, value) {
-  var propertyInfo = getPropertyInfo(name);
+  const propertyInfo = getPropertyInfo(name);
 
   if (propertyInfo && shouldSetAttribute(name, value)) {
     if (shouldIgnoreValue(propertyInfo, value)) {
@@ -164,8 +164,8 @@ export function setValueForProperty(node, name, value) {
       // `toString`ed by IE8/9.
       node[propertyInfo.propertyName] = value;
     } else {
-      var attributeName = propertyInfo.attributeName;
-      var namespace = propertyInfo.attributeNamespace;
+      const attributeName = propertyInfo.attributeName;
+      const namespace = propertyInfo.attributeNamespace;
       // `setAttribute` with objects becomes only `[object]` in IE8/9,
       // ('' + value) makes it output the correct toString()-value.
       if (namespace) {
@@ -217,10 +217,10 @@ export function deleteValueForAttribute(node, name) {
  * @param {string} name
  */
 export function deleteValueForProperty(node, name) {
-  var propertyInfo = getPropertyInfo(name);
+  const propertyInfo = getPropertyInfo(name);
   if (propertyInfo) {
     if (propertyInfo.mustUseProperty) {
-      var propName = propertyInfo.propertyName;
+      const propName = propertyInfo.propertyName;
       if (propertyInfo.hasBooleanValue) {
         node[propName] = false;
       } else {

packages/react-dom/src/client/ReactDOM.js

@@ -72,8 +72,12 @@ const {
 const {updatedAncestorInfo} = validateDOMNesting;
 const {precacheFiberNode, updateFiberProps} = ReactDOMComponentTree;
 
+let SUPPRESS_HYDRATION_WARNING;
+let topLevelUpdateWarnings;
+let warnOnInvalidCallback;
+
 if (__DEV__) {
-  var SUPPRESS_HYDRATION_WARNING = 'suppressHydrationWarning';
+  SUPPRESS_HYDRATION_WARNING = 'suppressHydrationWarning';
   if (
     typeof Map !== 'function' ||
     Map.prototype == null ||
@@ -90,7 +94,7 @@ if (__DEV__) {
     );
   }
 
-  var topLevelUpdateWarnings = (container: DOMContainer) => {
+  topLevelUpdateWarnings = (container: DOMContainer) => {
     if (__DEV__) {
       if (
         container._reactRootContainer &&
@@ -137,7 +141,7 @@ if (__DEV__) {
     }
   };
 
-  var warnOnInvalidCallback = function(callback: mixed, callerName: string) {
+  warnOnInvalidCallback = function(callback: mixed, callerName: string) {
     warning(
       callback === null || typeof callback === 'function',
       '%s(...): Expected the last optional `callback` argument to be a ' +