JavaScript - Function Expressions

Overview

Estimated time: 20–30 minutes

Function expressions create functions as values, enabling callbacks and higher-order programming.

Learning Objectives

• Create anonymous and named function expressions.
• Pass functions as arguments and assign to variables.

Prerequisites

• JavaScript - Functions

Examples

const add = function(a, b) { return a + b; };

// Named function expression (useful for debug stacks)
const factorial = function fact(n) {
  return n <= 1 ? 1 : n * fact(n - 1);
};

// Callback usage
[1,2,3].map(function(x){ return x * 2; });

Common Pitfalls

• Anonymous expressions show as "(anonymous)" in stack traces; prefer naming complex ones.