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Array-extensions

Exercise to Extend Array prototype adding a very useful functional programming helpers.

1. each(callback) method

Method executes a provided function once per array element.

  • Sintax

         array.each(callback)

  • Parameters

    • callback Function to execute for each element, taking 2 arguments:
      • currentValue The current element being processed in the array.
      • index The index of the current element being processed in the array.

2. where(spec) method

Creates a new array that contains all the elements that satisfies the given specification.

  • Sintax

        array.where(spec)

  • Parameters

    • spec Function that decide if the element shall or not to be included on the new array.
      • currentValue The current element being processed in the array.

3. any(spec) method

This method shall return a true value if any of the elements in the array satisfies the given spec.

  • Sintax

    array.any(spec)

  • Parameters

    • spec If the spec is a function then it shall be called for each element in the array, whenever the spec function returns a true value then immediately stop execution and returns true. In case that spec parameter is not a function object, then it will be tested against each element of the array.

4. select(spec) method.

Creates a new collection containing the elements returned by the spec function.

  • Sintax

        array.select(spec)

  • Parameters

    • spec Function to execute for each element and should return a value.

5. take(howMany, spec) method

Creates a new array containing ideally howMany elements, it could be less but no more.

  • Sintax

        array.take(howMany, spec)

  • Parameters

    • howMany the size of array result if there are enough elements.
    • spec Function to execute for each element and returns true or false.

6. skip(howMany) method.

Creates a new Array which will not include the first howMany elements.

  • Sintax

        array.skip(howMany)

  • Parameters howMany the size of array result if there are enough elements.

7. first(spec) method

Returns the first element on collection that satisfies the specification. This method could return a null value if the collection is empty or if there is not match element.

  • Sintax

        array.first(spec)

  • Parameters

    • spec Function or null value

##8. last(spec) method Returns last element on collection that satisfies the specification. This methoud could return a null value if the colllection is empty or if there is not match element.

  • Sintax 
        array.last(number => number % 2 === 0)
  • Parameters
    • spec Function or null value

##9. count(spec) method Returns the number of elements on the collection that satisfies the specification if no specification is present then it will return the array's length.

  • Syntax 
        array.count(number => number > 2)
  • Parameters
    • spec Function or null value

##10. index(spec) method Returns the zero based position in the array of the element that satisfies the specification. The specification can be either an object value or a function.

  • Syntax

        array.index(number => number === 1)
    array.index(1)

  • Parameters

    • spec Function or object value

##11. pluck(property) method Returns a new array containing that property value for each element on the array.

  • Syntax

        array.pluck('property')

  • Parameters

    • property String representing a name property

12. sum(spec) method.

Returns the summatory of the result of executing spec function on each arrays element. If there is not a spec function will return the summatory of the array's elements. Note: that if you have elements that are not numbers it will concatenate string.

  • Syntax 
        array.sum(x => x * 2)
  • Parameters
    • property Function or null value

13. max(comparator) method

Return the maximum value on the collection, a null value is return if the array is empty. If not comparator is specified then it evaluates the array elements as if they are numbers.

  • Syntax 
        array.max((a, b) => a.age - b.age)
  • Parameters
    • comparator Function or null value

14. min(comparator) method

Return the minimum value on the collection, a null value is return if the array is empty. If not comparator is specified then it evaluates the array elements as if they are numbers.

  • Syntax 
         array.min((a, b) => a.age - b.age)
  • Parameters
    • comparator Function or null value

15. flatten() method.

Returns a new flat array, It extracts from the inner arrays and inserted in the container array in the same position