function defaultMapFn(data) {
  return Object.keys(data).slice(0, this.headers.length).map(function(key) {
    return data[key]
  })
}
function defaultMapFn(data) {
  return Object.keys(data).slice(0, this.headers.length).map(function(key) {
    return data[key]
  })
}
function defaultMapFn ( data ) { return Object . keys ( data ) . slice ( 0 , this . headers . length ) . map ( function ( key ) { return data [ key ] } ) }
Default map will take the first this.header.length items from the object as
the row values
Default map will take the first this . header . length items from the object as the row values