(function () {

  function contains (array, value) {

    var doesContain = false

​

    for (var i = 0, length = array.length; i < length; i++) {

      if (array[i] === value) {

        doesContain = true

        break

      }

    }

​

    return doesContain

  }

  var nums = [1, 2, 3, 4, 5]

  console.log(nums)

  console.log(contains(nums, 3))

  console.log(contains(nums, 0))

  console.log(contains(nums, 4.2))

})()