Compose

easycodingJavaScriptFunctionsFunctional Programming~10 min

Asked at Google, Meta, Amazon

Overview

Implement compose(...fns) that returns a function applying functions from right to left.

Constraints

Each function takes and returns one value.
No functions = identity.

Examples

compose(x => x + 1, x => x * 2)(3); // 7

Solution

Reveal solution

function compose(...fns) {
  return function(x) {
    return fns.reduceRight((acc, fn) => fn(acc), x);
  };
}

compose.js

Compose

easycodingJavaScriptFunctions

Overview

Implement compose(...fns) that returns a function applying functions from right to left.

Constraints

Each function takes and returns one value.
No functions = identity.

Examples

compose(x => x + 1, x => x * 2)(3); // 7

Solution

Reveal solution

function compose(...fns) {
  return function(x) {
    return fns.reduceRight((acc, fn) => fn(acc), x);
  };
}

NameTopicDifficulty

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