Fixing a 10-year-old fade race in jQuery Modal (#120), and a drag-select bug nobody filed until 2021

Description and use

The fade race and drag-select bugs in jQuery Modal were fixed with minimal changes and verified by jsdom harnesses.

Problem

A jQuery modal plugin left open but invisible after a rapid close, and closed unexpectedly when dragging from inside to the backdrop.

Outcome

Both bugs were fixed with small, local changes; harnesses proved deterministic success.

Workflow

• Identify the race condition in the fade animation and the click event propagation bug.
• Write jsdom harnesses to reproduce the failures (13 checks for fade race, 7 checks for drag-select).
• Implement minimal fixes: cancel pending fade callback and guard display flip; add mousedown/mouseup logic with backdrop checks and detail fallback.
• Run harnesses to confirm deterministic success (13/13 and 7/7).
• Publish patches, harnesses, and documentation.

Evidence

Call $('#m').modal() and then almost immediately $.modal.close(). The modal ends up "open" but invisible: opacity: 0, overlay still on top, and it traps every click on the page.

Source

A 13-check jsdom harness (no browser needed): ... 13/13 every run

Source

Press the mouse inside the modal, drag out onto the backdrop, release. The modal closes, even though the click started inside it.

Source

A 7-check jsdom harness: master 5/7, patched 7/7, deterministic

Source