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The keypress event is triggered when a user presses a key on their keyboard. This event can be used to do things like restrict the input that a user can enter, or to show an error message if the user enters an invalid character.   To prevent the keypress event, you can use the preventDefault() method. This method is called on the event object that is passed to the event listener function. The following code shows how to prevent the keypress event from being triggered when a user presses a letter key on the name input field: const nameInput = document . getElementById ( 'fname' ); nameInput. addEventListener ( 'keypress' , function ( event ) { const allowedCharacters = /^[a-zA-Z]+$/ ; if (!allowedCharacters. test (event. key )) { event. preventDefault (); } });   In this code, the allowedCharacters regular expression is used to check if the key that the user pressed is a letter. If the key is not a letter, the prev