Deep Map

mediumcodingJavaScriptObjectsRecursion~25 min

Asked at Google, Meta, Amazon

Overview

Implement deepMap(value, fn) that recursively applies fn to every primitive value in a nested object/array.

Examples

deepMap({ a: 1, b: { c: 2 }}, x => x * 2); // { a: 2, b: { c: 4 }}

Solution

Reveal solution

function deepMap(value, fn) {
  if (value === null || typeof value !== 'object') return fn(value);
  if (Array.isArray(value)) return value.map(item => deepMap(item, fn));
  const result = {};
  for (const [k, v] of Object.entries(value)) result[k] = deepMap(v, fn);
  return result;
}

deep-map.js

Deep Map

mediumcodingJavaScriptObjects

Overview

Implement deepMap(value, fn) that recursively applies fn to every primitive value in a nested object/array.

Examples

deepMap({ a: 1, b: { c: 2 }}, x => x * 2); // { a: 2, b: { c: 4 }}

Solution

Reveal solution

function deepMap(value, fn) {
  if (value === null || typeof value !== 'object') return fn(value);
  if (Array.isArray(value)) return value.map(item => deepMap(item, fn));
  const result = {};
  for (const [k, v] of Object.entries(value)) result[k] = deepMap(v, fn);
  return result;
}

NameTopicDifficulty

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