Clean up event listeners from previous renders

[gggritso]

Fixes #615, which I introduced in #613, apologies!

The code calls instance.off(eventName, events[eventName]) where events is the new onEvents passed on the current component render. This is incorrect! The handlers on the instance are not what was passed on onEvents, they're wrapped in a function:

        instance.on(eventName, (param) => { // This is the actual bound listener
          func(param, instance); // `func` is what was passed in `onEvents`
        });

In this PR, I'm keeping track of the actual handlers that were bound on the previous render, and unbinding them correctly on subsequent re-renders.

Other approaches are possible. The most obvious one is to revert to running instance.off(eventName) but this will re-create the bug in #613. We can avoid the bug by manually re-binding the "finished" event if the component instance is still initializing.

The test for this case is nasty, lots of async work and timeouts. Hard to avoid because Promise is used internally, maybe others have better ideas?

[coveralls]

coverage: 94.737%. remained the same
when pulling edde2b7 on gggritso:fix/unbind-listeners
into 6bbc4c5 on hustcc:master.

[gggritso]

@hustcc apologies for the disruption! Would you mind taking a look at this PR?

[Copilot]

Pull request overview

This pull request fixes a bug where event listeners from previous renders were not being properly cleaned up, leading to multiple handlers being attached to the same event. The issue was introduced in PR #613 where the cleanup code attempted to unbind handlers using the original function references, but the actual handlers bound to the ECharts instance were wrapped functions.

Changes:

• Added tracking of wrapped event handlers in a private onEvents property
• Modified bindEvents to store references to the actual wrapped handlers
• Replaced offEvents with unbindEvents that correctly unbinds using stored handler references
• Added test to verify that only one handler remains bound after re-render

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/core.tsx	Added onEvents property to track wrapped handlers; modified bindEvents to store handler references; replaced offEvents with unbindEvents that correctly cleans up stored handlers
tests/charts/simple-spec.tsx	Added test data (legend and second series) and new test case verifying proper event handler cleanup on re-render

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[hustcc]

• echarts-for-react@3.0.6 Have a try!