How I Fixed Flutter Web’s Annoying Page Reload Problem
Have you ever been filling out a long form on a website, accidentally hit F5 (or Command+R), and watched everything you just typed disappear into thin air? If you build web apps with Flutter, this happens more often than you think. When compiling Flutter for the web, we get amazing performance, especially with WebAssembly (WASM). But the browser environment comes with one brutal reality: the…
Web developers often face the frustrating issue of losing unsaved changes when refreshing a page in a Flutter web application. This problem occurs because the in-memory variables reset to null or 0 upon page reload. To address this, developers frequently turn to packages like shared_preferences for key-value storage. However, these packages introduce another inconvenience: the Startup UI Flicker.
This flicker is caused by the asynchronous nature of Future-based APIs used by standard key-value storage packages, which require waiting for microtasks to resolve before updating the UI. This results in a split-second jump in the displayed text when the user hits refresh – the original value (such as "Guest") briefly appears before being replaced by the saved value (e.g., "Alex").
Several real-world scenarios demonstrate the impact of this flicker on user experience. For example, users may lose progress on an unfinished form draft, have to reselect product filters and categories in e-commerce applications, experience stale data in multi-tab admin dashboards, and suffer loss of navigation history when deep linking to specific pages.
Flutter's flutter_web_storage package offers a solution to eliminate this flicker by bypassing the asynchronous microtask queue entirely. It achieves this through direct synchronous JavaScript interop with the browser's DOM APIs, specifically window.localStorage and window.sessionStorage, allowing for instant hydration of the state during the app's initialization.
Additionally, flutter_web_storage implements a Tab Teardown Guard using the onbeforeunload event listener to ensure that any queued updates are flushed to browser storage when a user abruptly closes or reloads a tab. The package also employs cross-tab event broadcasting through native browser StorageEvent triggers to update subsequent tabs instantly when a user modifies values in another tab.
To use flutter_web_storage, developers simply need to add the package to their pubspec.yaml file and include the necessary code snippets for saving and retrieving values, as well as configuring the application's MaterialApp with navigatorObservers and initialRoute settings. By adopting flutter_web_storage, developers can significantly improve the user experience of their Flutter web applications by preventing the Startup UI Flicker and ensuring that user-entered data remains intact across page refreshes.
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