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This function cancels an event and prevents it from bubbling up.
Parameters:
- event – reference to the event name to cancel
Example:
In this example, we prevent the onclick event if other fields on the screen are not validated properly.
Note: We assume that validated() is a custom-built function that is available for use. We also assume that validated() returns true or false to indicate the validity of certain fields on the screen.The following can be used on the onkeydown event to restrict which keys can be pressed.
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function gradeKeys(event, element) { var submitButtonkey = getObj("my_button"); submitButton.onclick = function(event) { if(!validated()) //if fields on the screen are not valid { preventEvent(*event*); }event.keyCode; switch (key) { case 65: // allow A case 66: // allow B case 67: // allow C case 68: // allow D case 70: // allow F case 8: // allow backspace case 46: // allow delete case 37: // allow left arrow case 39: // allow right arrow case 40: // allow down arrow case 38: // allow up arrow case 13: // allow enter break; default: // disallow all other keys preventEvent(event); } } |