Cancel a keystroke in jQuery

Is is possible (cross-browser compatible) to CANCEL a keystroke after a user h开发者_运维知识库as made it (for example on a textbox)

The code I currently use edits the textbox value after the keystroke has been displayed:

$('.number').keypress(function() {
    this.value = this.value.replace(/[^0-9\.]/g, '');
});

$('.number').keypress(function() {
    if ( this.value == 'foobar' ){
        // "Cancel" keystroke
        return false;
    }
    this.value = this.value.replace(/[^0-9\.]/g, '');
});

SOLVED (AND UPDATED)

Apologies, I didnt test the most obvious option - which worked:

$('.number').keypress(function(event) {
    return /[0-9\.]/.test(String.fromCharCode(event.keyCode));
});