Code Refactoring Assistant

Based on the information you've provided, here are some suggestions to refactor your JavaScript code. 
Your original code creates a new array that contains the doubled values of the even numbers from the original array. It uses a for loop to iterate over the array, an if condition to check for even numbers, and then it pushes the doubled value of the even number to the new array.
This can be simplified by using higher-order functions that JavaScript provides like filter() and map(), which align well with the functional programming paradigm you mentioned. 
The filter() method creates a new array with all elements that pass the condition implemented by the provided function, and the map() method creates a new array with the result of calling a provided function on every element in the array.
Here's how your refactored code would look using ES6 syntax:
const array = [1, 2, 3, 4, 5];
const newArray = array.filter(num => num % 2 === 0).map(num => num * 2);

Here's what the new code does:

array.filter(num => num % 2 === 0): This line of code uses the filter() method to create a new array that includes only the even numbers from the original array.
.map(num => num * 2): This line of code is chained onto the previous one and uses the map() method to take the resulting array of even numbers and create a new array that contains those numbers doubled.

This refactored code does exactly the same thing as your original code but in a more readable and concise manner. It should also handle large datasets efficiently.
In terms of future-proofing your code for more complex filtering conditions, you can replace the arrow function inside the filter() and map() methods with more complex functions as needed.