Deep Merge

mediumcodingJavaScriptObjectsRecursion~25 min

Asked at Google, Stripe, Shopify

Overview

Implement deepMerge(target, source) that recursively merges source into target. Source values overwrite target for non-object values. Objects are merged recursively.

Examples

deepMerge({ a: 1, b: { c: 2 }}, { b: { d: 3 }, e: 4 });
// { a: 1, b: { c: 2, d: 3 }, e: 4 }

Solution

Reveal solution

function deepMerge(target, source) {
  const result = { ...target };
  for (const [key, val] of Object.entries(source)) {
    if (val && typeof val === 'object' && !Array.isArray(val)
        && result[key] && typeof result[key] === 'object' && !Array.isArray(result[key])) {
      result[key] = deepMerge(result[key], val);
    } else {
      result[key] = val;
    }
  }
  return result;
}

deep-merge.js

Deep Merge

mediumcodingJavaScriptObjects

Overview

Implement deepMerge(target, source) that recursively merges source into target. Source values overwrite target for non-object values. Objects are merged recursively.

Examples

deepMerge({ a: 1, b: { c: 2 }}, { b: { d: 3 }, e: 4 });
// { a: 1, b: { c: 2, d: 3 }, e: 4 }

Solution

Reveal solution

function deepMerge(target, source) {
  const result = { ...target };
  for (const [key, val] of Object.entries(source)) {
    if (val && typeof val === 'object' && !Array.isArray(val)
        && result[key] && typeof result[key] === 'object' && !Array.isArray(result[key])) {
      result[key] = deepMerge(result[key], val);
    } else {
      result[key] = val;
    }
  }
  return result;
}

NameTopicDifficulty

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