How to manipulate default value retrieved from x-ray scraper (node.js)

This is my code:

var Xray = require('x-ray');  
var x = Xray();
x('http://someurl.com', 'tr td:nth-child(2)', [{  
    text: 'a',
    url: 'a@href'
  }]).write('results.json')

I need to populate the field named "text" only with the first word from each a tag. An example of a tag value:

"FirstWord SecondWord ThirdWord"

The actual result is text: FirstWord SecondWord ThirdWord

Desired result text: FirstWord

I can postprocess the result.json file but i don´t like that way.

There is a fork of x-ray library made by cbou
It's custom x-ray API has a function prepare that can change the output
https://github.com/cbou/x-ray#xrayprepare-str--fn

Example:

function uppercase(str) {
  return str.toUpperCase();
}

xray('mat.io')
.prepare('uppercase', uppercase)
.select('title | uppercase')
.run(function(err, title) {
  // title == MAT.IO
});