Events and their handling in HTML world

Arun Rajeevan
2 min readJan 2, 2019

--

Type of Html Events:
https://developer.mozilla.org/en-US/docs/Web/Events

Creating an Event in Html world:
https://developer.mozilla.org/en-US/docs/Web/Guide/Events/Creating_and_triggering_events

Cancelling an Event:
https://developer.mozilla.org/en-US/docs/Web/API/Event/cancelable

On-event handlers:
https://developer.mozilla.org/en-US/docs/Web/Guide/Events/Event_handlers

Note: Each object can have only one on-event handler for a given event .Use addEventListener() to apply various event handlers independently from each other.

How the events propagate in HTML by default?

Event dispatch and DOM event flow

Applications can dispatch event objects using the dispatchEvent() method, and the event object will propagate through the DOM tree as determined by the DOM event flow.

Event objects are dispatched to an event target. But before dispatch can begin, the event object’s propagation path must first be determined.

The propagation path is an ordered list of current event targets through which the event passes. This propagation path reflects the hierarchical tree structure of the document. The last item in the list is the event target, and the preceding items in the list are referred to as the target’s ancestors, with the immediately preceding item as the target’s parent.

Once the propagation path has been determined, the event object passes through one or more event phases. There are three event phases: capture phase, target phase and bubble phase. Event objects complete these phases as described below. A phase will be skipped if it is not supported, or if the event object’s propagation has been stopped.
For example, if the bubble attribute is set to false, the bubble phase will be skipped, and if stopPropagation() has been called prior to the dispatch, all phases will be skipped.

  • The capture phase: The event object propagates through the target’s ancestors from the Window to the target’s parent.
  • The target phase: The event object arrives at the event object’s event target.If the event type indicates that the event doesn’t bubble, then the event object will halt after completion of this phase.
  • The bubble phase: The event object propagates through the target’s ancestors in reverse order, starting with the target’s parent and ending with the Window. This phase is also known as the bubbling phase.

--

--

No responses yet