<div>
<div data-bind="event: { mouseover: enableDetails, mouseout: disableDetails }">
Mouse over me
</div>
<div data-bind="visible: detailsEnabled">
Details
</div>
</div>
<script type="text/javascript">
var viewModel = {
detailsEnabled: ko.observable(false),
enableDetails: function() {
this.detailsEnabled(true);
},
disableDetails: function() {
this.detailsEnabled(false);
}
};
ko.applyBindings(viewModel);
</script>

<ul data-bind="foreach: places">
<li data-bind="text: $data, event: { mouseover: $parent.logMouseOver }"> </li>
</ul>
<p>You seem to be interested in: <span data-bind="text: lastInterest"> </span></p>
<script type="text/javascript">
function MyViewModel() {
var self = this;
self.lastInterest = ko.observable();
self.places = ko.observableArray(['London', 'Paris', 'Tokyo']);

// The current item will be passed as the first parameter, so we know which place was hovered over
self.logMouseOver = function(place) {
self.lastInterest(place);
}
}
ko.applyBindings(new MyViewModel());
</script>

<div data-bind="event: { mouseover: myFunction }">
Mouse over me
</div>
<script type="text/javascript">
var viewModel = {
myFunction: function(data, event) {
if (event.shiftKey) {
//do something different when user has shift key down
} else {
//do normal action
}
}
};
ko.applyBindings(viewModel);
</script>

<div data-bind="event: { mouseover: function(data, event) { myFunction('param1', 'param2', data, event) } }">
Mouse over me
</div>

<button data-bind="event: { mouseover: myFunction.bind($data, 'param1', 'param2') }">
Click me
</button>

<div data-bind="event: { mouseover: myDivHandler }">
<button data-bind="event: { mouseover: myButtonHandler }, mouseoverBubble: false">
Click me
</button>
</div>