lib/fields/interval.js
function interval(start, end) {
  if (arguments.length === 1 && typeof start === 'string') {
    return start
  }
  else if (arguments.length === 2) {
    var interval = utils.args(arguments, 0)

    return interval.map(function(original) {
      var arg = utils.date(original)

      if (!arg) {
        throw new FieldError('Bad date specified: ' + original)
      }

      return JSON.stringify(arg).replace(/"/g, '')
    }).join('/')
  }
  else {
    throw new FieldError('Bad arguments')
  }
}
function interval(start, end) {
  if (arguments.length === 1 && typeof start === 'string') {
    return start
  }
  else if (arguments.length === 2) {
    var interval = utils.args(arguments, 0)

    return interval.map(function(original) {
      var arg = utils.date(original)

      if (!arg) {
        throw new FieldError('Bad date specified: ' + original)
      }

      return JSON.stringify(arg).replace(/"/g, '')
    }).join('/')
  }
  else {
    throw new FieldError('Bad arguments')
  }
}
function interval ( start , end ) { if ( arguments . length === 1 && typeof start === 'string' ) { return start } else if ( arguments . length === 2 ) { var interval = utils . args ( arguments , 0 ) return interval . map ( function ( original ) { var arg = utils . date ( original ) if ( ! arg ) { throw new FieldError ( 'Bad date specified: ' + original ) } return JSON . stringify ( arg ) . replace ( / " / g , '' ) } ) . join ( '/' ) } else { throw new FieldError ( 'Bad arguments' ) } }
Generate interval string

@param {string|number|Date} start Start time or interval string
@param {string|number|Date} [end] End time
@returns {string} Interval string
Generate interval string