What causes "Invalid value "{value}" for attribute F supplied." in parallax/jsPDF?

Assign only integer bitmasks to F, or use the boolean helpers (showWhenPrinted) which manipulate bits correctly.

parallax/jsPDF · error · Error

Invalid value "{value}" for attribute F supplied.

Error message

Invalid value "{value}" for attribute F supplied.

What it means

Thrown by the AcroFormField.F setter when the assigned value is NaN. F is the annotation Flags entry (PDF spec Table 165) and must be an integer bitmask; the setter guards with isNaN. The default is 4 (Print). Note: isNaN(undefined) is false and isNaN('') is false, so empty string/undefined sneak through, but true non-numeric strings throw.

Source

Thrown at src/modules/acroform.js:1030

 * @class AcroFormField
 * @classdesc An AcroForm FieldObject
 */
var AcroFormField = function() {
  AcroFormPDFObject.call(this);

  //Annotation-Flag See Table 165
  var _F = 4;
  Object.defineProperty(this, "F", {
    enumerable: false,
    configurable: false,
    get: function() {
      return _F;
    },
    set: function(value) {
      if (!isNaN(value)) {
        _F = value;
      } else {
        throw new Error(
          'Invalid value "' + value + '" for attribute F supplied.'
        );
      }
    }
  });

  /**
   * (PDF 1.2) If set, print the annotation when the page is printed. If clear, never print the annotation, regardless of wether is is displayed on the screen.
   * NOTE 2 This can be useful for annotations representing interactive pushbuttons, which would serve no meaningful purpose on the printed page.
   *
   * @name AcroFormField#showWhenPrinted
   * @default true
   * @type {boolean}
   */
  Object.defineProperty(this, "showWhenPrinted", {
    enumerable: true,
    configurable: true,
    get: function() {

View on GitHub (pinned to a3930ce03a)

Solutions

Assign only integer bitmasks to F, or use the boolean helpers (showWhenPrinted) which manipulate bits correctly.
Coerce with Number() and validate isFinite before assignment.
Leave F at its default unless you specifically need a non-default annotation flag.

Example fix

// before
field.F = 'printable'; // throws

// after
field.F = 4; // bit 3 = Print
// or use the helper
field.showWhenPrinted = true;

Defensive patterns

Strategy: validation

Validate before calling

function setF(field, value) {
  var n = Number(value);
  if (!isFinite(n)) throw new Error('F must be a numeric bitmask, got ' + value);
  field.F = n;
}

Type guard

function isNumericFlag(v) {
  return typeof v === 'number' && isFinite(v);
}

Try / catch

try {
  field.F = value;
} catch (e) {
  if (/attribute F supplied/.test(e.message)) {
    field.F = Number(value) || 4;
  } else throw e;
}

Prevention

Assign integer bitmasks to F, or use the boolean helpers like showWhenPrinted.
Validate flag values are finite numbers before assignment.
Leave F at its default (4) unless you need a specific annotation flag.

When it happens

Trigger: Assigning field.F = 'abc' or field.F = NaN, or assigning an object; indirectly, a computed flag value that became NaN.

Common situations: Trying to set the print/annotation flag with a descriptive string instead of a bitmask; chaining bit operations that yielded NaN.

Related errors

AI-assisted analysis of parallax/jsPDF@a3930ce03a (2026-08-13). Data as JSON: /api/errors/f99b61fb9bb7aea1. Report an issue: GitHub.