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addEventListener

Create a new subscription to a smart contract’s events being emitted.

Usage​

Use the name of the event as it appears on the smart contract to subscribe to it.

In the example below, the listener will be called whenever the TokensMinted event is emitted by the contract.

const unsubscribe = contract.events.addEventListener(
  "TokensMinted",
  (event) => {
    // Perform some logic when the event is emitted
    console.log(event);
  },
);

Configuration​

eventName​

The name of the event to listen to.

In Solidity, an event is triggered by the emit keyword.

Example.sol
// An example Solidity contract
emit TokensMinted(); // Triggering event

To listen to this event, use the name of the event as it appears in the contract.

const unsubscribe = contract.events.addEventListener(
  "TokensMinted",
  (event) => {}, // Perform some logic
);

listener​

The callback function to be called when the event is emitted.

The function comes with an event parameter that contains the event data, in the type of Record<string, any>, (an object).

const unsubscribe = contract.events.addEventListener(
  "TokensMinted",
  (event) => {
    console.log(event);
  },
);

Return Value​

Returns a function that can be called to unsubscribe the listener.

To stop listening to events, call the function.

const unsubscribe = contract.events.addEventListener(
  "TokensMinted",
  (event) => {
    console.log(event);
  },
);

// Stop listening to the events
unsubscribe();