Add option to prefer const over let for immutable variables

10 files changed, 27 insertions, 26 deletions

diff --git a/.eslintrc b/.eslintrc
index 5ed0f7b370..cb65306d20 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -13,6 +13,7 @@
   },
   "plugins": [ "react", "flowtype" ],
   "rules": {
+    "prefer-const": "warn",
     "no-console": "off",
     "no-loop-func": "warn",
     "new-cap": "off",
diff --git a/app/components/Connect.js b/app/components/Connect.js
index fbb743854d..d14b768d44 100644
--- a/app/components/Connect.js
+++ b/app/components/Connect.js
@@ -316,7 +316,7 @@ export default class Connect extends Component<ConnectProps, ConnectState> {
   }
 
   networkSecurityStyle(): Types.Style {
-    let classes = [styles.status_security];
+    const classes = [styles.status_security];
     if (this.props.connection.status === 'connected') {
       classes.push(styles.status_security__secure);
     } else if (this.props.connection.status === 'disconnected') {
diff --git a/app/components/HeaderBar.js b/app/components/HeaderBar.js
index 69578bacfa..fcd7d40733 100644
--- a/app/components/HeaderBar.js
+++ b/app/components/HeaderBar.js
@@ -24,7 +24,7 @@ export default class HeaderBar extends Component<HeaderBarProps> {
   };
 
   render() {
-    let containerClass = [
+    const containerClass = [
       styles['headerbar'],
       platformStyles[process.platform],
       styles['style_' + this.props.style],
diff --git a/app/components/Settings.js b/app/components/Settings.js
index 33fc371faa..ad90e034c4 100644
--- a/app/components/Settings.js
+++ b/app/components/Settings.js
@@ -67,10 +67,10 @@ export default class Settings extends Component<SettingsProps> {
 
     let isOutOfTime = false,
       formattedExpiry = '';
-    let expiryIso = this.props.account.expiry;
+    const expiryIso = this.props.account.expiry;
 
     if (isLoggedIn && expiryIso) {
-      let expiry = moment(this.props.account.expiry);
+      const expiry = moment(this.props.account.expiry);
       isOutOfTime = expiry.isSameOrBefore(moment());
       formattedExpiry = (expiry.fromNow(true) + ' left').toUpperCase();
     }
diff --git a/app/lib/backend.js b/app/lib/backend.js
index c7b4ca53ec..b24b495449 100644
--- a/app/lib/backend.js
+++ b/app/lib/backend.js
@@ -264,7 +264,7 @@ export class Backend {
 
   async connect() {
     try {
-      let currentState = await this._ipc.getState();
+      const currentState = await this._ipc.getState();
       if (currentState.state === 'secured') {
         log.debug('Refusing to connect as connection is already secured');
         this._store.dispatch(connectionActions.connected());
diff --git a/app/lib/keyframe-animation.js b/app/lib/keyframe-animation.js
index 7a8968eb35..2961412230 100644
--- a/app/lib/keyframe-animation.js
+++ b/app/lib/keyframe-animation.js
@@ -124,7 +124,7 @@ export default class KeyframeAnimation {
   }
 
   play(options: KeyframeAnimationOptions = {}) {
-    let { startFrame, endFrame, beginFromCurrentState, advanceTo } = options;
+    const { startFrame, endFrame, beginFromCurrentState, advanceTo } = options;
 
     if (startFrame !== undefined && endFrame !== undefined) {
       if (startFrame < 0 || startFrame >= this._numFrames) {
@@ -216,7 +216,7 @@ export default class KeyframeAnimation {
       return;
     }
 
-    let lastFrame = this._frameRange[this._reverse ? 0 : 1];
+    const lastFrame = this._frameRange[this._reverse ? 0 : 1];
     if (this._currentFrame === lastFrame) {
       // mark animation as finished if it's not repeating
       if (!this._repeat) {
diff --git a/app/main.js b/app/main.js
index c6bade7719..64c341dc60 100644
--- a/app/main.js
+++ b/app/main.js
@@ -255,9 +255,9 @@ const ApplicationMain = {
     switch (process.platform) {
       case 'win32': {
         // Windows: %ALLUSERSPROFILE%\{appname}
-        let programDataDirectory = process.env.ALLUSERSPROFILE;
+        const programDataDirectory = process.env.ALLUSERSPROFILE;
         if (programDataDirectory) {
-          let appDataDirectory = path.join(programDataDirectory, appDirectoryName);
+          const appDataDirectory = path.join(programDataDirectory, appDirectoryName);
           return path.join(appDataDirectory, rpcAddressFileName);
         } else {
           throw new Error('Missing %ALLUSERSPROFILE% environment variable');
@@ -413,7 +413,7 @@ const ApplicationMain = {
   },
 
   _addContextMenu(window: BrowserWindow) {
-    let menuTemplate = [
+    const menuTemplate = [
       { role: 'cut' },
       { role: 'copy' },
       { role: 'paste' },
@@ -425,7 +425,7 @@ const ApplicationMain = {
     window.webContents.on(
       'context-menu',
       (_e: Event, props: { x: number, y: number, isEditable: boolean }) => {
-        let inspectTemplate = [
+        const inspectTemplate = [
           {
             label: 'Inspect element',
             click() {
diff --git a/test/components/Login.spec.js b/test/components/Login.spec.js
index 90bb70f4b3..ce7f347acf 100644
--- a/test/components/Login.spec.js
+++ b/test/components/Login.spec.js
@@ -8,7 +8,7 @@ import AccountInput from '../../app/components/AccountInput';
 
 describe('components/Login', () => {
   it('notifies on the first change after failure', () => {
-    let onFirstChange = spy();
+    const onFirstChange = spy();
     const props = {
       account: Object.assign({}, defaultAccount, {
         status: 'failed',
diff --git a/test/components/Settings.spec.js b/test/components/Settings.spec.js
index f564902c2a..ffdf0bf545 100644
--- a/test/components/Settings.spec.js
+++ b/test/components/Settings.spec.js
@@ -168,7 +168,7 @@ describe('components/Settings', () => {
   });
 
   it('should call external links callback', () => {
-    let collectedExternalLinkTypes: Array<string> = [];
+    const collectedExternalLinkTypes: Array<string> = [];
     const props = makeProps(loggedOutAccountState, settingsState, {
       onExternalLink: (type) => {
         collectedExternalLinkTypes.push(type);
diff --git a/test/keyframe-animation.spec.js b/test/keyframe-animation.spec.js
index 926bb79625..08a177ea79 100644
--- a/test/keyframe-animation.spec.js
+++ b/test/keyframe-animation.spec.js
@@ -14,7 +14,7 @@ describe('lib/keyframe-animation', function() {
   };
 
   it('should play sequence', (done) => {
-    let seq = [];
+    const seq = [];
     const animation = newAnimation();
     animation.onFrame = () => {
       seq.push(animation._currentFrame);
@@ -29,7 +29,7 @@ describe('lib/keyframe-animation', function() {
   });
 
   it('should play one frame', (done) => {
-    let seq = [];
+    const seq = [];
     const animation = newAnimation();
     animation.onFrame = () => {
       seq.push(animation._currentFrame);
@@ -44,7 +44,7 @@ describe('lib/keyframe-animation', function() {
   });
 
   it('should play sequence with custom frames', (done) => {
-    let seq = [];
+    const seq = [];
     const animation = newAnimation();
     animation.onFrame = () => {
       seq.push(animation._currentFrame);
@@ -62,7 +62,7 @@ describe('lib/keyframe-animation', function() {
   });
 
   it('should play sequence with custom frames in reverse', (done) => {
-    let seq = [];
+    const seq = [];
     const animation = newAnimation();
     animation.onFrame = () => {
       seq.push(animation._currentFrame);
@@ -81,7 +81,7 @@ describe('lib/keyframe-animation', function() {
   });
 
   it('should begin from current state starting below range', (done) => {
-    let seq = [];
+    const seq = [];
     const animation = newAnimation();
     animation.onFrame = () => {
       seq.push(animation._currentFrame);
@@ -103,7 +103,7 @@ describe('lib/keyframe-animation', function() {
   });
 
   it('should begin from current state starting below range reverse', (done) => {
-    let seq = [];
+    const seq = [];
     const animation = newAnimation();
     animation.onFrame = () => {
       seq.push(animation._currentFrame);
@@ -126,7 +126,7 @@ describe('lib/keyframe-animation', function() {
   });
 
   it('should begin from current state starting above range', (done) => {
-    let seq = [];
+    const seq = [];
     const animation = newAnimation();
     animation.onFrame = () => {
       seq.push(animation._currentFrame);
@@ -148,7 +148,7 @@ describe('lib/keyframe-animation', function() {
   });
 
   it('should begin from current state starting above range reverse', (done) => {
-    let seq = [];
+    const seq = [];
     const animation = newAnimation();
     animation.onFrame = () => {
       seq.push(animation._currentFrame);
@@ -171,7 +171,7 @@ describe('lib/keyframe-animation', function() {
   });
 
   it('should play sequence in reverse', (done) => {
-    let seq = [];
+    const seq = [];
     const animation = newAnimation();
     animation.onFrame = () => {
       seq.push(animation._currentFrame);
@@ -187,7 +187,7 @@ describe('lib/keyframe-animation', function() {
   });
 
   it('should play sequence on repeat', (done) => {
-    let seq = [];
+    const seq = [];
     const animation = newAnimation();
     const expectedFrames = [0, 1, 2, 3, 4, 0, 1, 2, 3, 4];
 
@@ -206,7 +206,7 @@ describe('lib/keyframe-animation', function() {
   });
 
   it('should play sequence on repeat in reverse', (done) => {
-    let seq = [];
+    const seq = [];
     const animation = newAnimation();
     const expectedFrames = [4, 3, 2, 1, 0, 4, 3, 2, 1, 0];
 
@@ -226,7 +226,7 @@ describe('lib/keyframe-animation', function() {
   });
 
   it('should alternate sequence', (done) => {
-    let seq = [];
+    const seq = [];
     const animation = newAnimation();
     const expectedFrames = [0, 1, 2, 3, 4, 3, 2, 1, 0];
 
@@ -246,7 +246,7 @@ describe('lib/keyframe-animation', function() {
   });
 
   it('should alternate reverse sequence', (done) => {
-    let seq = [];
+    const seq = [];
     const animation = newAnimation();
     const expectedFrames = [4, 3, 2, 1, 0, 1, 2, 3, 4];