Event Flow
Consider the situation when there are 2 elements nested together. Both have event handlers registered on the same event type, say "click". When the user clicks on the inner element, there are two possible ways to handle it:
- Trigger the elements from outer to inner (event capturing). This model is implemented in Netscape Navigator.
- Trigger the elements from inner to outer (event bubbling). This model is implemented in Internet Explorer and other browsers.
W3C takes a middle position in this struggle. Events are first captured until it reaches the target element, and then bubbled up. During the event flow, an event can be responded to at any element in the path (an observer) in either phase by causing an action, and/or by stopping the event (with method event.stopPropagation for W3C-conforming browsers and command event.cancelBubble = true for Internet Explorer), and/or by cancelling the default action for the event.
Read more about this topic: DOM Events
Famous quotes containing the words event and/or flow:
“It is known that Whistler when asked how long it took him to paint one of his “nocturnes” answered: “All of my life.” With the same rigor he could have said that all of the centuries that preceded the moment when he painted were necessary. From that correct application of the law of causality it follows that the slightest event presupposes the inconceivable universe and, conversely, that the universe needs even the slightest of events.”
—Jorge Luis Borges (1899–1986)
“There St. John mingles with my friendly bowl
The feast of reason and the flow of soul;”
—Alexander Pope (1688–1744)