Mastering Closures in JavaScript: A Practical Guide

Take your JavaScript skills to the next level by understanding closures and how to use them effectively in your code

Photo by David Everett Strickler on Unsplash

Closures are a fundamental concept in JavaScript, yet many developers find them confusing or difficult to understand. At their core, closures are simply functions that have access to variables from their outer (enclosing) function. This can be incredibly powerful, allowing you to create private variables, encapsulate functionality, and avoid naming collisions.

Here’s an example of a closure in action:

function counter() {
  let count = 0;
  
  return function incrementCounter() {
    count++;
    console.log(count);
  }
}

const myCounter = counter();
myCounter(); // logs 1
myCounter(); // logs 2
myCounter(); // logs 3
// ...and so on

In this example, counter is a factory function that returns another function, incrementCounter. The incrementCounter function has access to the variable count, which is defined in its enclosing scope. Each time we call myCounter(), it increments the value of count and logs it to the console. Because count is declared with the let keyword, it is not accessible outside of the counter function, ensuring that our counter remains private and cannot be accidentally…