Emulate Android back button with Esc

www/assets/js/main.js

@@ -50,6 +50,28 @@ router.on("pageInit", function (pagedata) {
     });
 });
 
+/**
+ * Perform back button behavior.
+ * Call this function whenever the equivalent to the Android back button is pressed.
+ * @returns {undefined}
+ */
+function handleBackButton() {
+    // Close map sheet if it's open
+    if ($(".sheet-modal").hasClass("modal-in")) {
+        app.sheet.close();
+    } else if (scanningBarcode) {
+        return;
+    } else {
+        router.back({force: true, ignoreCache: true});
+    }
+}
+
+$(document).keyup(function (e) {
+    if (e.key === "Escape" || e.keyCode == 27) {
+        handleBackButton();
+    }
+});
+
 router.on("routeChange", function (newRoute) {
     console.log("Info", "Navigating to ", newRoute.path);
 });

www/assets/js/platform.js

@@ -24,6 +24,8 @@ var scanBarcode = function (success, error) {
     app.dialog.alert("You can't scan barcodes with this device.", "Sorry!");
 }
 
+var scanningBarcode = false;
+
 var getLocation = function (success, error) {
     if ("geolocation" in navigator) {
         navigator.geolocation.getCurrentPosition(function (position) {
@@ -68,6 +70,7 @@ function setupHTML5BarcodeScanner() {
     $("body").append('<script src="node_modules/@zxing/library/umd/index.min.js"></script>');
 
     scanBarcode = function (success, error) {
+        scanningBarcode = true;
         $("#web-barcode-ui").removeClass("hidden");
         // Stolen from https://zxing-js.github.io/library/examples/multi-camera/
         const codeReader = new ZXing.BrowserMultiFormatReader();
@@ -83,6 +86,7 @@ function setupHTML5BarcodeScanner() {
                     selectedDeviceId = videoInputDevices[0].deviceId;
 
                     codeReader.decodeFromInputVideoDeviceContinuously(selectedDeviceId, 'barcode-viewer', (result, err) => {
+                        scanningBarcode = false;
                         if (result) {
                             codeReader.reset();
                             $("#web-barcode-ui").addClass("hidden");
@@ -99,10 +103,12 @@ function setupHTML5BarcodeScanner() {
                     });
                 })
                 .catch((err) => {
+                    scanningBarcode = false;
                     console.error(err);
                 });
         $("#web-barcode-ui").on("click", function () {
             codeReader.reset();
+            scanningBarcode = false;
             $("#web-barcode-ui").addClass("hidden");
         });
     };
@@ -111,14 +117,7 @@ function setupHTML5BarcodeScanner() {
 function initCordova() {
     platform_type = "cordova";
     // Handle back button to close things
-    document.addEventListener("backbutton", function (event) {
-        // Close map sheet if it's open
-        if ($(".sheet-modal").hasClass("modal-in")) {
-            app.sheet.close();
-        } else {
-            router.back({force: true, ignoreCache: true});
-        }
-    }, false);
+    document.addEventListener("backbutton", handleBackButton, false);
     document.addEventListener("deviceready", function () {
         if (getStorage("wakelock") == "true") {
             window.powerManagement.acquire(function () {
@@ -144,13 +143,16 @@ function initCordova() {
 
     if (typeof device != "undefined" && device.platform != "browser") {
         scanBarcode = function (success, error) {
+            scanningBarcode = true;
             cordova.plugins.barcodeScanner.scan(
                     function (result) {
+                        scanningBarcode = false;
                         if (!result.cancelled) {
                             success(result.text);
                         }
                     },
                     function (err) {
+                        scanningBarcode = false;
                         if (typeof error == "function") {
                             error(err);
                         }