Replace a bunch of `let` with `const`

According to https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/const

> Many style guides (including MDN's) recommend using const over let whenever a
variable is not reassigned in its scope. This makes the intent clear that a
variable's type (or value, in the case of a primitive) can never change.

internal/ui/static/js/bootstrap.js

@@ -2,7 +2,7 @@ document.addEventListener("DOMContentLoaded", () => {
     handleSubmitButtons();
 
     if (!document.querySelector("body[data-disable-keyboard-shortcuts=true]")) {
-        let keyboardHandler = new KeyboardHandler();
+        const keyboardHandler = new KeyboardHandler();
         keyboardHandler.on("g u", () => goToPage("unread"));
         keyboardHandler.on("g b", () => goToPage("starred"));
         keyboardHandler.on("g h", () => goToPage("history"));
@@ -48,7 +48,7 @@ document.addEventListener("DOMContentLoaded", () => {
         keyboardHandler.listen();
     }
 
-    let touchHandler = new TouchHandler();
+    const touchHandler = new TouchHandler();
     touchHandler.listen();
 
     if (WebAuthnHandler.isWebAuthnSupported()) {
@@ -56,7 +56,7 @@ document.addEventListener("DOMContentLoaded", () => {
 
         onClick("#webauthn-delete", () => { webauthnHandler.removeAllCredentials(); });
 
-        let registerButton = document.getElementById("webauthn-register");
+        const registerButton = document.getElementById("webauthn-register");
         if (registerButton != null) {
             registerButton.disabled = false;
 
@@ -65,13 +65,13 @@ document.addEventListener("DOMContentLoaded", () => {
             });
         }
 
-        let loginButton = document.getElementById("webauthn-login");
+        const loginButton = document.getElementById("webauthn-login");
         if (loginButton != null) {
             const abortController = new AbortController();
             loginButton.disabled = false;
 
             onClick("#webauthn-login", () => {
-                let usernameField = document.getElementById("form-username");
+                const usernameField = document.getElementById("form-username");
                 if (usernameField != null) {
                     abortController.abort();
                     webauthnHandler.login(usernameField.value).catch(err => WebAuthnHandler.showErrorMessage(err));
@@ -89,7 +89,7 @@ document.addEventListener("DOMContentLoaded", () => {
     onClick(":is(a, button)[data-action=markPageAsRead]", (event) => handleConfirmationMessage(event.target, markPageAsRead));
     onClick(":is(a, button)[data-toggle-status]", (event) => handleEntryStatus("next", event.target));
     onClick(":is(a, button)[data-confirm]", (event) => handleConfirmationMessage(event.target, (url, redirectURL) => {
-        let request = new RequestBuilder(url);
+        const request = new RequestBuilder(url);
 
         request.withCallback((response) => {
             if (redirectURL) {
@@ -127,7 +127,7 @@ document.addEventListener("DOMContentLoaded", () => {
     onClick(".header nav li", (event) => onClickMainMenuListItem(event));
 
     if ("serviceWorker" in navigator) {
-        let scriptElement = document.getElementById("service-worker-script");
+        const scriptElement = document.getElementById("service-worker-script");
         if (scriptElement) {
             navigator.serviceWorker.register(scriptElement.src);
         }

internal/ui/static/js/dom_helper.js

@@ -4,17 +4,17 @@ class DomHelper {
     }
 
     static openNewTab(url) {
-        let win = window.open("");
+        const win = window.open("");
         win.opener = null;
         win.location = url;
         win.focus();
     }
 
     static scrollPageTo(element, evenIfOnScreen) {
-        let windowScrollPosition = window.pageYOffset;
-        let windowHeight = document.documentElement.clientHeight;
-        let viewportPosition = windowScrollPosition + windowHeight;
-        let itemBottomPosition = element.offsetTop + element.offsetHeight;
+        const windowScrollPosition = window.pageYOffset;
+        const windowHeight = document.documentElement.clientHeight;
+        const viewportPosition = windowScrollPosition + windowHeight;
+        const itemBottomPosition = element.offsetTop + element.offsetHeight;
 
         if (evenIfOnScreen || viewportPosition - itemBottomPosition < 0 || viewportPosition - element.offsetTop > windowHeight) {
             window.scrollTo(0, element.offsetTop - 10);

internal/ui/static/js/keyboard_handler.js

@@ -12,7 +12,7 @@ class KeyboardHandler {
 
     listen() {
         document.onkeydown = (event) => {
-            let key = this.getKey(event);
+            const key = this.getKey(event);
             if (this.isEventIgnored(event, key) || this.isModifierKeyDown(event)) {
                 return;
             }
@@ -23,8 +23,8 @@ class KeyboardHandler {
 
             this.queue.push(key);
 
-            for (let combination in this.shortcuts) {
-                let keys = combination.split(" ");
+            for (const combination in this.shortcuts) {
+                const keys = combination.split(" ");
 
                 if (keys.every((value, index) => value === this.queue[index])) {
                     this.queue = [];
@@ -64,7 +64,7 @@ class KeyboardHandler {
             'Right': 'ArrowRight'
         };
 
-        for (let key in mapping) {
+        for (const key in mapping) {
             if (mapping.hasOwnProperty(key) && key === event.key) {
                 return mapping[key];
             }

internal/ui/static/js/modal_handler.js

@@ -8,7 +8,7 @@ class ModalHandler {
     }
 
     static getFocusableElements() {
-        let container = this.getModalContainer();
+        const container = this.getModalContainer();
 
         if (container === null) {
             return null;
@@ -18,14 +18,14 @@ class ModalHandler {
     }
 
     static setupFocusTrap() {
-        let focusableElements = this.getFocusableElements();
+        const focusableElements = this.getFocusableElements();
 
         if (focusableElements === null) {
             return;
         }
 
-        let firstFocusableElement = focusableElements[0];
-        let lastFocusableElement = focusableElements[focusableElements.length - 1];
+        const firstFocusableElement = focusableElements[0];
+        const lastFocusableElement = focusableElements[focusableElements.length - 1];
 
         this.getModalContainer().onkeydown = (e) => {
             if (e.key !== 'Tab') {
@@ -57,13 +57,13 @@ class ModalHandler {
 
         this.activeElement = document.activeElement;
 
-        let container = document.createElement("div");
+        const container = document.createElement("div");
         container.id = "modal-container";
         container.setAttribute("role", "dialog");
         container.appendChild(document.importNode(fragment, true));
         document.body.appendChild(container);
 
-        let closeButton = document.querySelector("button.btn-close-modal");
+        const closeButton = document.querySelector("button.btn-close-modal");
         if (closeButton !== null) {
             closeButton.onclick = (event) => {
                 event.preventDefault();
@@ -89,7 +89,7 @@ class ModalHandler {
     }
 
     static close() {
-        let container = this.getModalContainer();
+        const container = this.getModalContainer();
         if (container !== null) {
             container.parentNode.removeChild(container);
         }

internal/ui/static/js/touch_handler.js

@@ -15,8 +15,8 @@ class TouchHandler {
 
     calculateDistance() {
         if (this.touch.start.x >= -1 && this.touch.move.x >= -1) {
-            let horizontalDistance = Math.abs(this.touch.move.x - this.touch.start.x);
-            let verticalDistance = Math.abs(this.touch.move.y - this.touch.start.y);
+            const horizontalDistance = Math.abs(this.touch.move.x - this.touch.start.x);
+            const verticalDistance = Math.abs(this.touch.move.y - this.touch.start.y);
 
             if (horizontalDistance > 30 && verticalDistance < 70 || this.touch.moved) {
                 return this.touch.move.x - this.touch.start.x;
@@ -54,8 +54,8 @@ class TouchHandler {
         this.touch.move.x = event.touches[0].clientX;
         this.touch.move.y = event.touches[0].clientY;
 
-        let distance = this.calculateDistance();
-        let absDistance = Math.abs(distance);
+        const distance = this.calculateDistance();
+        const absDistance = Math.abs(distance);
 
         if (absDistance > 0) {
             this.touch.moved = true;
@@ -78,7 +78,7 @@ class TouchHandler {
         }
 
         if (this.touch.element !== null) {
-            let absDistance = Math.abs(this.calculateDistance());
+            const absDistance = Math.abs(this.calculateDistance());
 
             if (absDistance > 75) {
                 toggleEntryStatus(this.touch.element);
@@ -118,9 +118,9 @@ class TouchHandler {
             return;
         }
 
-        let distance = this.calculateDistance();
-        let absDistance = Math.abs(distance);
-        let now = Date.now();
+        const distance = this.calculateDistance();
+        const absDistance = Math.abs(distance);
+        const now = Date.now();
 
         if (now - this.touch.time <= 1000 && absDistance > 75) {
             if (distance > 0) {
@@ -138,10 +138,10 @@ class TouchHandler {
             return;
         }
 
-        let now = Date.now();
+        const now = Date.now();
 
         if (this.touch.start.x !== -1 && now - this.touch.time <= 200) {
-            let innerWidthHalf = window.innerWidth / 2;
+            const innerWidthHalf = window.innerWidth / 2;
 
             if (this.touch.start.x >= innerWidthHalf && event.changedTouches[0].clientX >= innerWidthHalf) {
                 goToPage("next");
@@ -158,19 +158,16 @@ class TouchHandler {
     }
 
     listen() {
-        let hasPassiveOption = DomHelper.hasPassiveEventListenerOption();
+        const hasPassiveOption = DomHelper.hasPassiveEventListenerOption();
 
-        let elements = document.querySelectorAll(".entry-swipe");
-
-        elements.forEach((element) => {
+        document.querySelectorAll(".entry-swipe").forEach((element) => {
             element.addEventListener("touchstart", (e) => this.onItemTouchStart(e), hasPassiveOption ? { passive: true } : false);
             element.addEventListener("touchmove", (e) => this.onItemTouchMove(e), hasPassiveOption ? { passive: false } : false);
             element.addEventListener("touchend", (e) => this.onItemTouchEnd(e), hasPassiveOption ? { passive: true } : false);
             element.addEventListener("touchcancel", () => this.reset(), hasPassiveOption ? { passive: true } : false);
         });
 
-        let element = document.querySelector(".entry-content");
-
+        const element = document.querySelector(".entry-content");
         if (element) {
             if (element.classList.contains("gesture-nav-tap")) {
                 element.addEventListener("touchend", (e) => this.onTapEnd(e), hasPassiveOption ? { passive: true } : false);

internal/ui/static/js/webauthn_handler.js

@@ -5,7 +5,7 @@ class WebAuthnHandler {
 
     static showErrorMessage(errorMessage) {
         console.log("webauthn error: " + errorMessage);
-        let alertElement = document.getElementById("webauthn-error");
+        const alertElement = document.getElementById("webauthn-error");
         if (alertElement) {
             alertElement.textContent += " (" + errorMessage + ")";
             alertElement.classList.remove("hidden");
@@ -79,14 +79,14 @@ class WebAuthnHandler {
             return;
         }
 
-        let credentialCreationOptions = await registerBeginResponse.json();
+        const credentialCreationOptions = await registerBeginResponse.json();
         credentialCreationOptions.publicKey.challenge = this.decodeBuffer(credentialCreationOptions.publicKey.challenge);
         credentialCreationOptions.publicKey.user.id = this.decodeBuffer(credentialCreationOptions.publicKey.user.id);
         if (Object.hasOwn(credentialCreationOptions.publicKey, 'excludeCredentials')) {
             credentialCreationOptions.publicKey.excludeCredentials.forEach((credential) => credential.id = this.decodeBuffer(credential.id));
         }
 
-        let attestation = await navigator.credentials.create(credentialCreationOptions);
+        const attestation = await navigator.credentials.create(credentialCreationOptions);
 
         let registrationFinishResponse;
         try {
@@ -108,7 +108,7 @@ class WebAuthnHandler {
             throw new Error("Login failed with HTTP status code " + response.status);
         }
 
-        let jsonData = await registrationFinishResponse.json();
+        const jsonData = await registrationFinishResponse.json();
         window.location.href = jsonData.redirect;
     }
 
@@ -121,7 +121,7 @@ class WebAuthnHandler {
             return;
         }
 
-        let credentialRequestOptions = await loginBeginResponse.json();
+        const credentialRequestOptions = await loginBeginResponse.json();
         credentialRequestOptions.publicKey.challenge = this.decodeBuffer(credentialRequestOptions.publicKey.challenge);
 
         if (Object.hasOwn(credentialRequestOptions.publicKey, 'allowCredentials')) {