30-seconds-of-code/snippets/compose.md

A collection of useful JavaScript snippets.

### compose

Performs right-to-left function composition.

Use `Array.reduce()` to perform right-to-left function composition.
The last (rightmost) function can accept one or more arguments; the remaining functions must be unary.

```js
const compose = (...fns) => fns.reduce((f, g) => (...args) => f(g(...args)));
```

```js
const add5 = x => x + 5;
const multiply = (x, y) => x * y;
const multiplyAndAdd5 = compose(
  add5,
  multiply
);
multiplyAndAdd5(5, 2); // 15
```