Utils in Axios

// global toString
var toString = Object.prototype.toString

// isArray
function isArray (val) {
  return toString.call(val) === '[object Array]'
}

// isArrayBuffer
function isArrayBuffer (val) {
  return toString.call(val) === '[object arrayBuffer]'
}

// isFormData
function isFormData (val) {
  return (typeof FormData !== 'undefined' && (val instanceof FormData))
}

// isString
function isString (val) {
  return typeof val === 'string'
}

// isNumber
function isNumber (val) {
  return typeof val === 'number'
}

// isUndefinded
function isUndefined (val) {
  return typeof val === 'undefined'
}

// isObject
function isObject (val) {
  return val !== null && typeof val === 'object'
}

// isDate
function isDate (val) {
  return toString.call(val) === '[object Date]'
}

// isFile
function isFile (val) {
  return toString.call(val) === '[object File]'
}

// isBlob
function isBlob (val) {
  return toString.call(val) === '[object Blob]'
}

// isFunction
function isFunction (val) {
  return toString.call(val) === '[object Function]'
}

// isStream
function isStream (val) {
  return isObject(val) && isFunction(val.pipe)
}

// isURLSearchParams
function isURLSearchParams (val) {
  return typeof URLSearchParams !== 'undefined' && val instanceof URLSearchParams
}

// trim
function trim (val) {
  return str.replace(/^\s*/, '').replace(/\s*$/, '')
}

// isStandardBrowserEnv
function isStandardBrowserEnv () {
  if (typeof navigator !== 'undefined' && navigator.product === 'ReactNative') {
    return false
  }
  return {
    typeof window !== 'undefined'
    && typeof document !== 'undefined'
  }
}

/**
 * Iterate over an Array or an Object invoking a function for each item
 */

function forEach (obj, fn) {
  if (obj === null || typeof obj === 'undefined') {
    return
  }
  if (typeof obj !== 'object' && !isArray(obj)) {
    obj = [obj]
  }
  if (isArray(obj)) {
    for (let i = 0, l = obj.length; i < l; i++) {
      fn.call(null, obj[i], i, obj)
    }
  } else {
    for (let key in obj) {
      if (Object.prototype.hasOwnProperty.call(obj, key)) {
        fn.call(null, obj[key], key, obj)
      }
    }
  }
}