pdf-lib node package for manipulate pdf template

 use pdf-lib to fill in pdf template:

export const fillForm = async (pdfDoc: any, fieldNames: string[], fieldValues: string[]) => {

  const form = pdfDoc.context.lookup(pdfDoc.catalog.get(PDFName.of('AcroForm')))

  if (!form) {

    throw new Error('PDF does not contain a form')

  }

  form.set(PDFName.of('NeedAppearances'), PDFBool.True)

  const fieldRefs = form.context.lookup(form.get(PDFName.of('Fields')))

  if (!fieldRefs) {

    throw new Error('PDF form does not contain any fields')

  }

  const fields = fieldRefs.array.map((ref: any) => form.context.lookup(ref))

  fields.forEach((field: any) => {

    const name = field.get(PDFName.of('T'))

    console.log('pdf form fieldName:', name, name.value)

    if (name) {

      const idx = fieldNames.indexOf(name.value)

      const newValue = idx >= 0 ? fieldValues[idx] : '' 

      if (newValue) {

        field.set(PDFName.of('V'), PDFString.of(newValue))

        field.set(PDFName.of('Ff'), PDFNumber.of(1))

      }

    }

  })

}

another good code:

https://github.com/YOU54F/serverless-pdf-filler/blob/serverless/src/utils/template.ts