Functional programming is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids changing-state and mutable data.

Imperative programming is a programming paradigm that uses statements that change a program's state.

In this post, we will explore the differences between these two paradigms and how they can be used together to create better software.

Imperative Programming

Functional Programming

Functional Programming Real World Example

Using reduce to calculate the total number of lines of code written by a team of developers (starting with 0).

const numbers = [1, 2, 3, 4, 5];
const doubleNumbers = [];

for (let i = 0; i < numbers.length; i++) {
  doubleNumbers.push(numbers[i] * 2);
}

const numbers = [1, 2, 3, 4, 5];
const doubleNumbers = numbers.map((number) => number * 2);

const employeeOutput = [
    {
        name: 'John',
        coding: 200,
    },
    {
        name: 'Jane',
        coding: 900,
    },
    {
        name: 'Bob',
        coding: 1200,
    },
];

const totalOutput = employeeOutput.reduce(
    (totalLines, output) => totalLines + output.coding, 0
);

console.log(totalOutput);