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This method registers an event handler on a DOM element.
To register a function as an event handler, the DOM element that you want to observe must already exist in the DOM
Event.observe(element,eventName,handler[,useCapture=false]); |
Here is explanation about passed parameters:
element: The DOM element you want to observe; as always in Prototype, this can be either an actual DOM reference, or the ID string for the element.
evenetName: The standardized event name, as per the DOM level supported by your browser. This includes click, mousedown, mouseup, mouseover, mousemove and mouseout.
handler: This is the event handler function. This can be an anonymous function you create on-the-fly.
useCapture: Optionally, you can request capturing instead of bubbling. The details are in the DOM Level 2 Events
Here is an example which observe click event and take an action whenever a click event occurs.
<html> <head> <title>Prototype examples</title> <script type="text/javascript" src="/javascript/prototype.js"> </script> <script> // Register event 'click' and associated call back. Event.observe(document, 'click', respondToClick); // Callback function to handle the event. function respondToClick(event) { alert("You pressed the button...." ); } </script> </head> <body> <p id="note"> Click anywhere to see the result.</p> <p id="para1">This is paragraph 1</p> <p id="para2">This is paragraph 2</p> <div id="division"> This is divsion. </div> </body> </html> |
To understand it in better way you can Try it yourself.
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