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devexamples

Deep Merge Configuration Objects

Merge nested config objects where later sources override earlier scalars but nested objects are combined recursively, a common layering need.

JavascriptConfig Management

Code

snippet
export function deepMerge(...sources) {
  const result = {};
  for (const source of sources) {
    if (!source || typeof source !== "object") continue;
    for (const [key, value] of Object.entries(source)) {
      const existing = result[key];
      if (isPlainObject(existing) && isPlainObject(value)) {
        result[key] = deepMerge(existing, value);
      } else if (Array.isArray(value)) {
        result[key] = value.slice();
      } else {
        result[key] = value;
      }
    }
  }
  return result;
}

function isPlainObject(value) {
  return value !== null && typeof value === "object" && !Array.isArray(value);
}

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