var numbers = [5, 7];

​

function calculate(operation) {

  return operation(this.numbers[0], this.numbers[1]);

}

​

function add(number1, number2) {

  return number1 + number2;

}

​

console.log(calculate(add));

​

(function() {

  var localScope = {

    numbers: [15, 21]

  };

  console.log(calculate.call(localScope, add));

})();