​

function constrainer(min, max) {

  return function(n) {

    return Math.max(min, Math.min(n, max));

  };

}

​

var constrain = constrainer(5, 10);

​

console.log(constrain(15)); //=> 10

console.log(constrain(-3)); //=> 5

console.log(constrain(7)); //=> 7