NodeJS
JavaScript Callback vs Higher Order Function: Key Differences
Introduction
As a friendly language for functional programming JavaScript contains two important concepts known as callback functions and higher-order functions. Both concepts belong to a similar category yet fulfill independent operational functions. This blog will examine the fundamental distinctions between callback functions and higher-order functions along with their suitable applications.
What is a Callback Function?
A callback function is a function that is passed as an argument to another function and is executed at a later time. Callback functions are commonly used for asynchronous operations, event handling and functional programming.
Example of a Callback Function
function greet(name, callback) { console.log(`Hello, ${name}!`); callback(); // Executes the callback function}function sayGoodbye() { console.log("Goodbye!");}greet("Alice", sayGoodbye);When to Use Callback Functions?
1. Asynchronous operations (e.g., setTimeout, API calls, event listeners)
2. The code responsible for event management operates within JavaScript (e.g. button.onclick = function)
3. The execution order of functions occurs according to a predetermined sequence
What is a Higher-Order Function?
A higher-order function serves as either an argument that accepts another function or functions as its output. HOFs make it possible to build functions that combine other functions which results in more effective code design as well as reusable logical structures.
Example of a Higher-Order Function (Taking a Function as an Argument)
function operate(a, b, operation) { return operation(a, b);}
function add(x, y) { return x + y;}console.log(operate(5, 3, add)); // Output: 8Example of a Higher-Order Function (Returning a Function)function multiplier(factor) { return function (num) { return num * factor; };}const double = multiplier(2);console.log(double(5)); // Output: 10Common Higher-Order Functions in JavaScript
- map(): Transforms an array based on a function
- filter(): Filters elements based on a condition
- reduce(): Aggregates values based on a function
Key Differences
Feature:
Callback Function
- A function passed as an argument to another function.
- Used for event handling, asynchronous operations, and executing logic later.
- Examples: setTimeout, event listeners, API responses.
- Is executed inside another function.
Higher Order Function
- A function that takes a function as an argument or returns a function.
- Used for function composition, data transformation, and reusable logic.
- Examples: map, filter, reduce, function factories.
- Defines how a function behaves with other functions
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