event_handeler

handel custom events just like JavaScript with some features and limitations

event handeler is built to be used with your any function call,like if you run a function and on function end you will dispatchCustomEvent and it will notify its all listeners with addCustomEventListener

• dispach custom events with value also
• listen to it and get the value in a callback function
• ✨Magic ✨

Features

• it can be used with your any function its very simple to use no need for any overhead of provider
• simple data passing and listen for changes and act according to it in another file/class.
• its a standalone function so you can use it any where no need for extras setup
• it will marge with your any function and give it a new life who can emmit changes made,
• when you add listener you can select which type/event you want to listen for
• event listener can run customcallback with event value so data passing accross multiple pages made super easy .
• multiple page support can be achived by utilizing local storage of device

I am somen das for any question or suggestions Email me also if you need an App 😉 Here is the

Methods

dispatchCustomEvent(eventvalue,eventType) addCustomEventListener(eventType, callback)

callback have the value of eventvalue

Examples

Install the dependencies and devDependencies and start.

For dispatching custom events when i add something to secureStorage

_storage .write(key: 'filterBy', value: "clear filters").then((value) {
dispatchCustomEvent("clear filters","filterChange");
});

To listen to this paricular event put this in initState under any function

StreamSubscription? eventSubscription=addCustomEventListener("filterChange", (eventvalue){
print(eventvalue);//prints clear filters
//do something you want when the event happens
    
});

📌 Problems & Solutions for Using Event Listeners in Flutter Widgets

❌ Problem 1: Memory Leak Due to Persistent Subscriptions

• If an event listener (addCustomEventListener) is used inside the build method, it keeps listening to events even after the widget is removed from the tree.
• This results in a memory leak because the listener is never disposed.

✅ Fix:

• Store the subscription in a variable and cancel it in the dispose method of StatefulWidget.

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❌ Problem 2: Multiple Subscriptions on Every Rebuild

• When a Flutter widget rebuilds, a new event listener is added every time.
• This causes duplicate event listeners, leading to multiple function calls for a single event.

✅ Fix:

• Store the subscription in the state (State class) instead of the build method.
• Ensure only one listener is active at a time.
• Cancel the existing subscription before adding a new one.

check provided example for better understanding

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