Functional programming is a programming paradigm that focuses on the use of pure functions, immutability, and function composition. In JavaScript, it is possible to apply many concepts of functional programming to improve code clarity and maintainability.

This image shows a diagram of functional programming

Pure Functions

A pure function is a function that always returns the same result for the same arguments and has no side effects. Pure functions are predictable and easy to test.

javascript

Immutability

Immutability implies not changing the original data. Instead of modifying an object or array, we create a new one. This is fundamental in functional programming as it prevents errors associated with shared state.

javascript

Function Composition

Function composition is the process of combining small functions to build more complex functions. By composing functions, we can create clearer and more reusable data flows.

javascript

Using map, filter, and reduce

The methods map, filter, and reduce are pillars of functional programming in JavaScript, allowing you to transform, filter, and accumulate data declaratively.

map

map applies a function to each element of an array, returning a new array.

javascript

filter

filter returns a new array containing only the elements that satisfy a condition.

javascript

reduce

reduce allows combining all elements of an array into a single value, such as a sum or product.

javascript

Avoiding Side Effects

In functional programming, we avoid side effects, which means not modifying values outside the function's scope. This keeps the code predictable and makes debugging easier.

javascript

Currying

Currying is the process of transforming a function that takes multiple arguments into a series of functions that take a single argument. This facilitates function reuse and composition.

javascript

Conclusion

Functional programming in JavaScript allows you to write clearer, modular, and side-effect-free code. By applying principles like pure functions, immutability, and composition, it is possible to build more maintainable and robust applications.