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flattenObject

Flattens a nested object into a single-level object whose keys are path strings.

  • Only plain objects and arrays are flattened; arrays use their indices as keys. (tags.0, tags.1)
  • Empty objects and empty arrays are kept as-is so their keys are not lost.
  • Non-plain values such as Date, Map, Set, File and class instances are kept as-is without being flattened.
  • Only the object's own enumerable string keys are processed, and the original object is not mutated.
  • Objects with circular references are not supported.

Code​

🔗 View source code


Interface​

typescript
function flattenObject<T extends Record<PropertyKey, any>>(
  obj: T,
  separator?: string // default: '.'
): Record<string, unknown>;

Usage​

typescript
import { flattenObject } from '@modern-kit/utils';

flattenObject({
  product: { id: 1, category: { name: 'clothing' } },
  tags: ['a', 'b'],
});
// { 'product.id': 1, 'product.category.name': 'clothing', 'tags.0': 'a', 'tags.1': 'b' }

// Custom separator
flattenObject({ a: { b: 1 } }, '_');
// { a_b: 1 }

// Empty objects/arrays and non-plain values are kept as-is.
flattenObject({ a: {}, b: [], c: new Date(0) });
// { a: {}, b: [], c: Date(0) }