Summary

Fixes gh-5751

The hasDataAttrs private flag was not cleared when .removeData() was called without a key argument. This prevented subsequent .data() calls from re-reading HTML5 data-* attributes, contrary to the documented behavior:

A later call to data() will [...] re-retrieve the value from the data- attribute.

Reproduction

const elem = $("<div data-test=\"123\">");
console.log(elem.data("test")); // 123
elem.removeData();
console.log(elem.data("test")); // Expected: 123, Actual before fix: undefined

Fix

Clear dataPriv's hasDataAttrs flag when .removeData() is called without a specific key (full data removal). When a key is passed, the flag is left intact since individual key removal should not trigger a full data-attr re-scan.

Test plan

Added QUnit test .removeData() clears hasDataAttrs so data-* attributes are re-read (gh-5751) verifying the documented behavior.