Disallow var

Summary: We're ES6 and `var`s scoping rules are weird. Let's block this.

Reviewed By: jknoxville

Differential Revision: D16131290

fbshipit-source-id: ba67d16bb8a185a4bb59a657a97b00230dbacafe

.eslintrc.js

@@ -21,6 +21,7 @@ module.exports = {
     'no-catch-shadow': 0, // only relevant for IE8 and below
     'no-bitwise': 0, // bitwise operations needed in some places
     'consistent-return': 0,
+    'no-var': 2,
     'max-len': 0, // let's take prettier take care of this
     indent: 0, // let's take prettier take care of this
     'no-console': 0, // we're setting window.console in App.js

headless/index.js

@@ -146,7 +146,7 @@ async function exitActions(
   store: Store,
 ): Promise<void> {
   const {metrics, exit} = userArguments;
-  for (var exitAction of exitClosures) {
+  for (let exitAction of exitClosures) {
     try {
       const action = await exitAction(userArguments, store);
       if (action.exit) {

src/__tests__/server.device.js

@@ -37,8 +37,8 @@ beforeAll(() => {
 });
 
 test('Device can connect successfully', done => {
-  var testFinished = false;
-  var disconnectedTooEarly = false;
+  let testFinished = false;
+  let disconnectedTooEarly = false;
   const registeredClients = [];
   server.addListener('new-client', (client: Client) => {
     // Check there is a connected device that has the same device_id as the new client

src/dispatcher/desktopDevice.js

@@ -12,7 +12,7 @@ import MacDevice from '../devices/MacDevice';
 import WindowsDevice from '../devices/WindowsDevice';
 
 export default (store: Store, logger: Logger) => {
-  var device;
+  let device;
   if (process.platform === 'darwin') {
     device = new MacDevice();
   } else if (process.platform === 'win32') {

src/fb-stubs/Logger.js

@@ -9,7 +9,7 @@ import type {TrackType, Logger} from '../fb-interfaces/Logger';
 import type {Store} from '../reducers/index';
 import ScribeLogger from './ScribeLogger';
 
-var instance: ?StubLogger = null;
+let instance: ?StubLogger = null;
 
 type Args = {
   isHeadless?: boolean,

src/plugins/cpu/index.js

@@ -6,7 +6,7 @@
  */
 
 import {FlipperDevicePlugin, Device} from 'flipper';
-var adb = require('adbkit-fb');
+let adb = require('adbkit-fb');
 import TemperatureTable from './TemperatureTable.js';
 
 import {

src/plugins/databases/index.js

@@ -165,7 +165,7 @@ function transformRow(
   index: number,
 ): TableBodyRow {
   const transformedColumns = {};
-  for (var i = 0; i < columns.length; i++) {
+  for (let i = 0; i < columns.length; i++) {
     transformedColumns[columns[i]] = {value: renderValue(row[i])};
   }
   return {key: String(index), columns: transformedColumns};

src/server.js

@@ -334,7 +334,7 @@ class ConnectionTracker {
   logConnectionAttempt(client: ClientQuery) {
     const key = `${client.os}-${client.device}-${client.app}`;
     const time = Date.now();
-    var entry = this.connectionAttempts.get(key) || [];
+    let entry = this.connectionAttempts.get(key) || [];
     entry.push(time);
     entry = entry.filter(t => t >= time - this.timeWindowMillis);
 

static/transforms/electron-stubs.js

@@ -5,10 +5,10 @@
  * @format
  */
 
-var babylon = require('@babel/parser');
-var fs = require('fs');
+let babylon = require('@babel/parser');
+let fs = require('fs');
 
-var electronStubs = babylon.parseExpression(
+let electronStubs = babylon.parseExpression(
   fs.readFileSync('static/electron-stubs.notjs').toString(),
 );