datetype.js

import { GraphQLScalarType } from 'graphql'
import { GraphQLError } from 'graphql/error'
import { Kind } from 'graphql/language'

function parseDate (value) {
  let result = new Date(value)
  if (isNaN(result.getTime())) {
    throw new TypeError('Invalid date: ' + value)
  }
  if (value !== result.toJSON()) {
    throw new TypeError('Invalid date format, only accepts: YYYY-MM-DDTHH:MM:SS.SSSZ: ' + value)
  }
  return result
}

export default new GraphQLScalarType({
  name: 'DateTime',

  // Serialize a date to send to the client.
  serialize (value) {
    if (!(value instanceof Date)) {
      throw new TypeError('Field error: value is not an instance of Date')
    }
    if (isNaN(value.getTime())) {
      throw new TypeError('Field error: value is an invalid Date')
    }
    return value.toJSON()
  },

  // Parse a date received as a query variable.
  parseValue (value) {
    if (typeof value !== 'string') {
      throw new TypeError('Field error: value is not an instance of string')
    }
    return parseDate(value)
  },

  // Parse a date received as an inline value.
  parseLiteral (ast) {
    if (ast.kind !== Kind.STRING) {
      throw new GraphQLError('Query error: Can only parse strings to dates but got a: ' + ast.kind, [ast])
    }
    try {
      return parseDate(ast.value)
    } catch (e) {
      throw new GraphQLError('Query error: ' + e.message, [ast])
    }
  }
})