Call a function when a CTRL + key is pressed

Trigger a function when a key is pressed.

function filterKeys()
{
if (window.event)
{
// captures the key combination of Ctrl and Shift keys
if(window.event.ctrlKey && window.event.shiftKey)
{
var key = window.event.keyCode;
// captures the key for upper and lower case F
if (key == 70 || key == 102)
//window.event.keyCode = 0; - do nothing
write a custom function here

}
}
}