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

Use one of the four exact PDF type strings with the leading slash: '/Btn', '/Tx', '/Ch', '/Sig'.

parallax/jsPDF · error · Error

Invalid value " " for attribute FT supplied.

Error message

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

What it means

Thrown by the AcroFormField.FT setter when value is not one of the four valid PDF field types: '/Btn' (button), '/Tx' (text), '/Ch' (choice), '/Sig' (signature). FT is the required Field Type entry (PDF spec). The setter uses a strict switch and rejects anything else, including common mistakes like 'text', 'TextField', or missing the leading slash.

Solutions

Use one of the four exact PDF type strings with the leading slash: '/Btn', '/Tx', '/Ch', '/Sig'.
Prefer the concrete field classes provided by the acroform module (Button, TextField, ChoiceField, etc.) which set FT correctly.
Whitelist the value before assignment.

Example fix

// before
field.FT = 'text'; // throws

// after
field.FT = '/Tx';
// or use the typed constructor
var tf = new doc.AcroFormTextField();

Defensive patterns

Strategy: validation

Validate before calling

var VALID_FT = ['/Btn', '/Tx', '/Ch', '/Sig'];
if (VALID_FT.indexOf(value) === -1) {
  throw new Error('FT must be one of ' + VALID_FT.join(', ') + ', got ' + value);
}
field.FT = value;

Type guard

function isValidFT(v) {
  return ['/Btn','/Tx','/Ch','/Sig'].indexOf(v) !== -1;
}

Try / catch

try {
  field.FT = value;
} catch (e) {
  if (/attribute FT supplied/.test(e.message)) {
    throw new Error("FT must be '/Btn', '/Tx', '/Ch', or '/Sig' (note the leading slash)");
  }
  throw e;
}

Prevention

Always include the leading slash: '/Tx', '/Btn', '/Ch', '/Sig'.
Use the typed field constructors (AcroFormTextField, etc.) which set FT correctly.
Whitelist the value before assignment.

When it happens

Trigger: Setting field.FT to a value without the leading slash (e.g. 'Tx'), a human-readable type name ('text','button'), or any unsupported type.

Common situations: Constructing a custom field and forgetting the '/'; copying a type from documentation that omitted the slash; assigning the wrong constant.

Related errors

AI-assisted analysis of parallax/jsPDF@a3930ce03a (2026-08-13). Data as JSON: /api/errors/1a69a283eb0abe64. Report an issue: GitHub.

Appendix: source

Thrown at src/modules/acroform.js:1197

  });

  var _FT = "";
  Object.defineProperty(this, "FT", {
    enumerable: true,
    configurable: false,
    get: function() {
      return _FT;
    },
    set: function(value) {
      switch (value) {
        case "/Btn":
        case "/Tx":
        case "/Ch":
        case "/Sig":
          _FT = value;
          break;
        default:
          throw new Error(
            'Invalid value "' + value + '" for attribute FT supplied.'
          );
      }
    }
  });

  var _T = null;

  Object.defineProperty(this, "T", {
    enumerable: true,
    configurable: false,
    get: function() {
      if (!_T || _T.length < 1) {
        // In case of a Child from a Radio´Group, you don't need a FieldName
        if (this instanceof AcroFormChildClass) {
          return undefined;
        }
        _T = "FieldObject" + AcroFormField.FieldNum++;

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