camelcase and camelcase-keys deep conversion: working versions (tested 2026-10-16)

{
  "name": "camelcase-keys-convert",
  "private": true,
  "type": "module",
  "scripts": {
    "test": "node --import tsx --test test/*.test.ts"
  },
  "dependencies": {
    "camelcase": "10.0.0",
    "camelcase-keys": "10.0.3"
  },
  "devDependencies": {
    "@types/node": "26.6.5",
    "tsx": "4.23.15"
  }
}

import camelCase from "camelcase";
import camelcaseKeys from "camelcase-keys";

export function toCamel(input: string): string {
  return camelCase(input);
}

export function toPascal(input: string): string {
  return camelCase(input, { pascalCase: true });
}

export function convertKeysDeep<T>(input: T): T {
  return camelcaseKeys(input as Record<string, unknown>, { deep: true }) as unknown as T;
}

import { test } from "node:test";
import assert from "node:assert/strict";
import { toCamel, toPascal, convertKeysDeep } from "../src/convert.ts";

test("camelcases a snake_case string", () => {
  assert.equal(toCamel("hello_world"), "helloWorld");
});

test("camelcases a string with pascalCase option", () => {
  assert.equal(toPascal("hello_world"), "HelloWorld");
});

test("deep converts snake_case keys including nested arrays", () => {
  const input = {
    user_id: 1,
    first_name: "Ada",
    home_address: {
      zip_code: "12345",
      geo_coords: { lat_long: [1, 2] },
    },
    order_items: [
      { item_id: "a", unit_price: 10 },
      { item_id: "b", unit_price: 20 },
    ],
  };

  const expected = {
    userId: 1,
    firstName: "Ada",
    homeAddress: {
      zipCode: "12345",
      geoCoords: { latLong: [1, 2] },
    },
    orderItems: [
      { itemId: "a", unitPrice: 10 },
      { itemId: "b", unitPrice: 20 },
    ],
  };

  assert.deepEqual(convertKeysDeep(input), expected);
});

test("deep converts a top level array of objects", () => {
  const input = [{ item_id: "a" }, { item_id: "b" }];
  assert.deepEqual(convertKeysDeep(input), [{ itemId: "a" }, { itemId: "b" }]);
});