Sibling component communication is one of the most confusing topics for developers working with Lightning Web Components (LWC). At first glance, it feels natural to expect sibling components to communicate directly with each other. When that doesn’t work, many developers immediately reach for Pub-Sub, often without fully understanding the long-term implications.
Salesforce encourages a more structured and scalable communication approach where the parent component acts as the coordinator. This design approach is known as the Mediator Pattern, and it is the recommended, enterprise-grade solution for sibling communication in LWC.
Let’s Learn with a Real-Time Example
Business Scenario
Imagine you are building a Lightning page that includes the following components:
- Account List – Displays a list of Accounts
- Account Details – Displays details of the selected Account
When a user selects an Account from the list, the Account Details component should update automatically.
Even though Account List and Account Details are sibling components, they cannot communicate directly. Instead, the parent component mediates the communication between them.
Step 1: Account List (Sibling A – Event Emitter)
The Account List component fires a custom event when an Account is selected.
Step 2: Parent Component – Mediator
The parent component listens to the custom event fired by the Account List component. It stores the selected Account Id and then passes that value down to the Account Details component.
This is the Mediator Pattern in action.
The parent:
- Acts as the central coordinator
- Maintains shared state
- Controls data flow between sibling components
Step 3: Account Details (Sibling B – Consumer)
The Account Details component receives the Account Id from the parent using a public @api property.
Whenever the value changes in the parent, the Account Details component updates automatically.
This component:
- Has no dependency on the Account List component
- Remains reusable and testable
- Automatically reacts to data changes
Why the Mediator Pattern Works So Well
The Mediator Pattern simplifies sibling communication by letting the parent component manage shared data. Sibling components remain independent, making the code easier to debug, extend, and reuse.
Because data flows in a single, predictable direction, applications built with this pattern are easier to scale and align perfectly with LWC best practices.
Conclusion
In Lightning Web Components, sibling components should never communicate directly with each other. All communication should flow through the parent component, which serves as the mediator.
By using:
- Custom Events for child-to-parent communication
- @api properties for parent-to-child data binding
Developers can create applications that are clean, maintainable, and scalable.
The Mediator Pattern is the recommended best practice for sibling communication in LWC and represents the gold standard for building robust, enterprise-grade component architectures in Salesforce.
By following the above blog instructions, you will be able to learn “The Mediator Pattern in LWC: How Sibling Components Really Communicate“. If you still have queries or any related problems, don’t hesitate to contact us at salesforce@greytrix.com. More details about our integration product are available on our website and Salesforce AppExchange.
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