Extract Data from PDF Form Fields Using JavaScript

You can extract the values of all the form fields present in a PDF using Instance#getFormFieldValues. It returns a simple JavaScript object, where the keys refer to the FormField#name of the form field and the value is either null, string, or Array<string>, depending upon the type of the FormField:

const formFieldValues = instance.getFormFieldValues();
console.log(formFieldValues); // { textField: 'Text Value', checkBoxField: ['A', 'B'], buttonField: null }

Extracting Form Data as Instant JSON

Instant JSON is optimized for annotations. However, generating Instant JSON from a document will include form field values as well.

Form fields that have been saved can be exported in the Instant JSON format using the Instance#exportInstantJSON API method, and you can look for their values within formFieldValues:

const instantJSON = await instance.exportInstantJSON();

const formFieldValues = instantJSON.formFieldValues;
console.log(formFieldValues); // [{"name":"Form Field","type":"pspdfkit/form-field-value","v":1]

Note that this method will only yield the changes (diff) in form field values after saving the document.