_.partial

partial_.partial(function, *arguments)
Partially apply a function by filling in any number of its arguments, without changing its dynamic this value. A close cousin of bind. You may pass _ in your list of arguments to specify an argument that should not be pre-filled, but left open to supply at call-time.

var subtract = function(a, b) { return b - a; };
sub5 = _.partial(subtract, 5);
sub5(20);
=> 15

// Using a placeholder
subFrom20 = _.partial(subtract, _, 20);
subFrom20(5);
=> 15