mouseup

Mouseup is a user input event that occurs when a user releases a previously pressed mouse button. It is commonly used in graphical user interfaces to finish a drag operation, trigger actions that started with a button press, or detect simple button interactions. In most systems, a mouseup event is distinct from mousedown (the press) and click (a press followed by a release on the same target).

In the document object model and other GUI toolkits, a mouseup event carries information about where the release happened and which button was released. Typical properties include button or which to indicate the released button, and coordinates such as clientX/clientY or pageX/pageY. The event usually bubbles up through the element hierarchy, allowing parent elements to respond to the release if needed. Some frameworks also expose a 'buttons' flag indicating buttons pressed at release.

Common uses include ending a drag-and-drop sequence, completing a drawing gesture, triggering a custom action when the user releases a pressed control, or implementing clickable controls that rely on release rather than press. Developers often check the event target or the element under the cursor to decide whether to execute an action, and may call preventDefault or stopPropagation to control behavior.

Cross-platform considerations: on touch devices, there is no mouse, so pointer events or touch events and gesture handling are used. For broad compatibility, many developers listen to pointerup in addition to mouseup and provide keyboard alternatives (such as Space or Enter) to activate controls. Understanding the precise event timing helps avoid accidental activations and ensures accessible, predictable interfaces.