nwjs/nw.js · error · TypeException

Expecting set(string, optional string, optional boolean) or

Error message

Expecting set(string, optional string, optional boolean) or set(ClipboardData[]) or set(ClipboardData).

What it means

Thrown by nw.Clipboard.set when arguments match none of the supported overloads: set(string[, string[, boolean]]), set(ClipboardData[]), or set(ClipboardData). The dispatcher checks Array tag, String tag, and argument count, then throws if nothing matches.

Source

Thrown at src/resources/api_nw_clipboard.js:64

    return nwClipboardBinding.getListSync([type])[0].data;
  }
  throw new TypeException('Expecting get(string, optional boolean) or get(ClipboardData[]) or get(ClipboardData).');
};
NWClipboard.prototype.set = function (content, type, raw) {
  var toString = $Object.prototype.toString;
  // set(ClipboardData[])
  if (arguments.length === 1 && toString.apply(content) === '[object Array]') {
    return nwClipboardBinding.setListSync(content);
  }
  // set(DOMString, DOMString, boolean)
  if (toString.apply(content) === '[object String]') {
    return nwClipboardBinding.setListSync([{type: type || 'text', raw: !!raw, data: content}]);
  }
  // set(ClipboardData)
  if (arguments.length === 1) {
    return nwClipboardBinding.setListSync([content]);
  }
  throw new TypeException('Expecting set(string, optional string, optional boolean) or set(ClipboardData[]) or set(ClipboardData).');
};
NWClipboard.prototype.clear = function () {
  return nwClipboardBinding.clearSync();
};
NWClipboard.prototype.readAvailableTypes = function() {
  return nwClipboardBinding.readAvailableTypes();
};

nwClipboardBinding['get'] = NWClipboard['get'];

View on GitHub (pinned to e15da848e9)

Solutions

Set text: `nw.Clipboard.set('hello', 'text')` or just `nw.Clipboard.set('hello')`.
Set multiple entries: `nw.Clipboard.set([{ type: 'text', data: 'hi' }])`.
Set a single ClipboardData: `nw.Clipboard.set({ type: 'text', data: 'hi' })`.

Example fix

// before
nw.Clipboard.set();
// after
nw.Clipboard.set('hello', 'text');

Defensive patterns

Strategy: validation

Validate before calling

function safeSet(content, type) {
  if (typeof content !== 'string' && !Array.isArray(content) && (typeof content !== 'object' || content === null))
    throw new TypeError('Invalid clipboard content');
  return nw.Clipboard.set(content, type);
}

Type guard

function isClipboardData(v) { return v && typeof v === 'object' && typeof v.type === 'string'; }

Try / catch

try { nw.Clipboard.set(content, type); } catch (e) { if (/Expecting set/.test(e.message)) nw.Clipboard.set(String(content), 'text'); else throw e; }

Prevention

Coerce content to a string before calling set for text.
Use ClipboardData objects for non-text types.

When it happens

Trigger: Calling `nw.Clipboard.set()` with no args, `nw.Clipboard.set(null)`, or `nw.Clipboard.set(123)`.

Common situations: Passing a number or object as content without wrapping it as a ClipboardData; forgetting the content argument when specifying only a type.

Related errors

AI-assisted analysis of nwjs/nw.js@e15da848e9 (2026-08-13). Data as JSON: /api/errors/23ce54ab72f7ee77. Report an issue: GitHub.