moy-fp/src/String/toString.js

A functional programming library.

import curry from '../Function/curry'

/**
 * * -> String
 */
const toString = curry(
  x => {
    switch(Object.prototype.toString.call(x)){
      case '[object Boolean]': return String(x)
      case '[object Date]': return String(x.valueOf())
      case '[object Number]': return Number.isNaN(x) ? 'NaN' : String(x)
      case '[object String]': return x
      case '[object RegExp]': return String(x)
      case '[object Null]': return 'null'
      case '[object Undefined]': return 'undefined'
      case '[object Array]': return `[${x.reduce((str, v, index, array) => `${str}${toString(v)}${index + 1 === array.length ? '' : ', '}`, '')}]`
      case '[object Object]': return `{${Object.entries(x).reduce((str, [key, value], index, array) => `${str}${key}: ${toString(value)}${index + 1 === array.length ? '' : ', '}`, '')}}`
      case '[object Function]': return x.name || 'anonymous'
      default: return x.toString ? x.toString() : 'unknownType'
    }
  }
)

export default toString