refactor main.js into smaller pieces, and moved navbar.js to assets

assets/scripts/core/device.js

@@ -0,0 +1,36 @@
+let deviceState = {
+  isMobile: false,
+  isTablet: false,
+  isLaptop: false,
+};
+
+function detectDeviceState() {
+  if (window.innerWidth <= 425) {
+    deviceState = {
+      isMobile: true,
+      isTablet: false,
+      isLaptop: false,
+    };
+  } else if (window.innerWidth <= 768) {
+    deviceState = {
+      isMobile: false,
+      isTablet: true,
+      isLaptop: false,
+    };
+  } else {
+    deviceState = {
+      isMobile: false,
+      isTablet: false,
+      isLaptop: true,
+    };
+  }
+}
+
+detectDeviceState();
+window.addEventListener('resize', detectDeviceState);
+
+// returns a copy of the device state
+// so other parts of code can't override this.
+export function getDeviceState() {
+  return { ... deviceState };
+}

assets/scripts/core/index.js

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+export * from './device';