JavaScript Higher-Order Functions

What are Higher-Order Functions?

Functions that take functions as arguments or return functions.

┌─────────────────────┐
│   Higher-Order      │
│   Function          │
│  ┌───────────────┐  │
│  │ Takes function │  │
│  │ OR            │  │
│  │ Returns func  │  │
│  └───────────────┘  │
└─────────────────────┘

Examples

// Function that takes function
function operate(a, b, operation) {
  return operation(a, b);
}

operate(5, 3, (x, y) => x + y); // 8

// Function that returns function
function multiplyBy(factor) {
  return (number) => number * factor;
}

const double = multiplyBy(2);
double(5); // 10

Key Takeaway

Higher-order functions work with other functions. Enable powerful patterns. Essential for functional programming.