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What are the differences between arrow functions and regular functions in JavaScript?

Submitted by: @import:30-seconds-of-code·Mar 2, 2026·

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Problem

JavaScript's arrow functions might seem the same as regular functions on the surface, but they have some very important differences:

Syntactical differences
this value (execution context)
Usage as methods
Usage as constructors

Solution

const square = a => a * a;

// Equivalent regular function
function square(a) {
  return a * a;
}

this value (execution context)
Usage as methods
Usage as constructors
arguments binding

The first and most obvious difference between arrow functions and regular functions is their syntax. Not only do they look different, but arrow functions also provide an implicit return shorthand and allow parenthesis around a single argument to be omitted.
Inside a regular function, execution context (i.e. the value of this) is dynamic. This means that the value of this depends on how the function was invoked (simple invocation, method invocation, indirect invocation or constructor invocation). On the other hand, an arrow function does not define its own execution context. This results in an arrow function's this being resolved lexically (i.e. the scope in which the arrow function was defined).

Code Snippets

const square = a => a * a;

// Equivalent regular function
function square(a) {
  return a * a;
}

function logThis() {
  console.log(this);
}
document.addEventListener('click', logThis);
// `this` refers to the document

const logThisArrow = () => {
  console.log(this);
};
document.addEventListener('click', logThisArrow);
// `this` refers to the global object

function logThis() {
  console.log(this);
}
logThis.call(42);       // Logs: 42

const logThisArrow = () => {
  console.log(this);
};
logThisArrow.call(42);  // Logs the global object

Context

From 30-seconds-of-code: arrow-regular-function-differences

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