[Bug] Treemap select, selects all elements with same name

[ThomasKro]

Version

6.0.0

Link to Minimal Reproduction

https://codepen.io/ThomasKro/pen/bNegOOY

Steps to Reproduce

1. Open reproduction link
2. Click on either "select"-button or "toggle select"-button
3. dispatchAction with the correlating action will be called for dataIndex 3

Current Behavior

Both elements with the name Volume 1 will be highlighted (Elements have different Ids and are in different parents)

Expected Behavior

Only the element with dataIndex 3 should be highlighted

Environment

- OS: Ubuntu
- Browser: Chrome 144.0.7559.59
- Framework: Vue@3

Any additional comments?

No response

[ChimdumebiNebolisa]

I’ve identified the root cause of this issue and opened a PR to fix it.

Summary of the Issue

When using dispatchAction({ type: 'select', dataIndex }) on a treemap that contains multiple nodes with the same name and no explicit id, the selection logic behaves incorrectly and can select multiple nodes or fail to target the intended one.

Root Cause

Treemap selection state is stored in selectedMap, which is keyed using a “selection key”.

Previously, this key was derived by preferring data.getName(dataIndex) over data.getId(dataIndex).

In treemaps, it is valid for multiple nodes to share the same name. When this happens:

• Multiple nodes generate the same selection key
• Entries collide in selectedMap
• dispatchAction({ type: 'select', dataIndex }) becomes non-deterministic

Fix

The fix updates the selection key to always use data.getId(dataIndex), which is guaranteed to be unique:

• Explicit id values are respected
• When id is not provided, ECharts auto-generates stable unique IDs (name__ec__N)
• Selection collisions are eliminated for duplicate names

This aligns treemap selection behavior with other series types and ensures dispatchAction works reliably.

Verification

A minimal reproduction case was added:

• test/treemap-select-21480.html
• Uses duplicate node names ("same")
• Dispatches a select action for a specific dataIndex
• Confirms only the intended node is selected (selectedIndices === [3])

PR

A PR has been opened containing:

• The core fix in src/model/Series.ts
• Updated dist artifacts
• A reproducible test case for validation

This resolves the issue without affecting existing behavior for series that already rely on IDs.

[helgasoft]

workaround in #18242 - see how @selunders appends zero-width spaces (\u200B)

[ChimdumebiNebolisa]

Thanks, that workaround makes sense. I agree it’s usable, but I’ll leave this open in case a name-independent selection model is preferred long term.