How do I preserve whitespace/formatting after parsing then re-stringifying a YAML Doc?

[jdvne]

I am using the following snippet to load a YAML formatted file, then immediately save it elsewhere:

  const fileContents = fs.readFileSync('./file.old', 'utf-8');
  const document = yaml.parseDocument(fileContents, {keepSourceTokens: true});
  fs.writeFile('./file.new', document.toString(), () => {});

However, when I compare the input and output

diff file.old file.new

I see that it does not preserve the whitespace and formatting of my original file

<       alarm_description: Alerts if number of 5XX Http Error Codes is more than 10 for 1 consecutive periods of 60 seconds
---
>       alarm_description: Alerts if number of 5XX Http Error Codes is more than 10 for
>         1 consecutive periods of 60 seconds
1215c1068
<         canary_options: [50, 100]
---
>         canary_options: [ 50, 100 ]

Is there a way to ensure that the stringified output is exactly the same as the parsed input? Thanks!

[eemeli]

For that you'll need to work with the CST API, as the Document level does not preserve whitespace.