オブジェクトのキーをキャメルケースtoスネークケースまたはスネークケースtoキャメルケースに変換する便利関数

convertCaseUtils.ts

type obj = {
  [key: string]: any
}

const typeOf = (obj: any): string => {
  return toString.call(obj).slice(8, -1).toLowerCase()
}

const camelToSnakeArray = (arr: any[]): any[] => {
  return arr.map((item: any) => {
    if (typeOf(item) === 'object') return camelToSnakeObject(item)
    if (typeOf(item) === 'array') return camelToSnakeArray(item)
    return item
  })
}

const camelToSnakeObject = (obj: obj): obj => {
  const result: obj = {}
  Object.keys(obj).forEach((key) => {
    result[key.replace(/([A-Z])/g, '_$1').toLowerCase()] = (() => {
      if (typeOf(obj[key]) === 'object') return camelToSnakeObject(obj[key])
      if (typeOf(obj[key]) === 'array') return camelToSnakeArray(obj[key])
      return obj[key]
    })()
  })
  return result
}

const snakeToCamelArray = (arr: any[]): any[] => {
  return arr.map((item: any) => {
    if (typeOf(item) === 'object') return snakeToCamelObject(item)
    if (typeOf(item) === 'array') return snakeToCamelArray(item)
    return item
  })
}

const snakeToCamelObject = (obj: obj): obj => {
  const result: obj = {}
  Object.keys(obj).forEach((key) => {
    result[key.replace(/_(\w)/g, (_, p1) => p1.toUpperCase())] = (() => {
      if (typeOf(obj[key]) === 'object') return snakeToCamelObject(obj[key])
      if (typeOf(obj[key]) === 'array') return snakeToCamelArray(obj[key])
      return obj[key]
    })()
  })
  return result
}