dianping/cat · error · TypeError

typeof prototype[{typeof prototype}] != 'object'

Error message

typeof prototype[{typeof prototype}] != 'object'

What it means

This is the es5-shim polyfill for Object.create bundled into worker-xquery.js. ES5 spec requires the first argument (the prototype) to be an object or null; the shim explicitly throws a TypeError with a diagnostic that embeds the actual typeof when a primitive is passed. Native engines throw a vaguer error, so this message is a shim-specific improvement.

Source

Thrown at cat-home/src/main/webapp/assets/js/editor/worker-xquery.js:49293

            empty.constructor =
            empty.hasOwnProperty =
            empty.propertyIsEnumerable =
            empty.isPrototypeOf =
            empty.toLocaleString =
            empty.toString =
            empty.valueOf =
            empty.__proto__ = null;
            return empty;
        }
    }

    Object.create = function create(prototype, properties) {
        var object;
        if (prototype === null) {
            object = createEmpty();
        } else {
            if (typeof prototype != "object")
                throw new TypeError("typeof prototype["+(typeof prototype)+"] != 'object'");
            var Type = function () {};
            Type.prototype = prototype;
            object = new Type();
            object.__proto__ = prototype;
        }
        if (properties !== void 0)
            Object.defineProperties(object, properties);
        return object;
    };
}

function doesDefinePropertyWork(object) {
    try {
        Object.defineProperty(object, "sentinel", {});
        return "sentinel" in object;
    } catch (exception) {
    }
}

View on GitHub (pinned to e815e74d4c)

Solutions

1. Check the value passed as prototype: it must be an object, a function (use MyCtor.prototype), or explicitly null.
2. If you want an empty dictionary-style object, use Object.create(null), not Object.create(undefined) or Object.create({}) with a missing variable.
3. Trace the argument upstream — this message tells you the runtime type, so log the variable before the call to find where it became a primitive.
4. If the call is inside a third-party library, update it: newer builds may already guard against primitives.

Example fix

// before
var proto = config.baseProto; // may be undefined/string
var obj = Object.create(proto);

// after
var proto = config.baseProto;
if (proto !== null && (typeof proto !== 'object' && typeof proto !== 'function')) {
  throw new TypeError('config.baseProto must be an object or null, got ' + typeof proto);
}
var obj = Object.create(proto);

function isValidPrototype(p) {
  return p === null || (typeof p === 'object') || (typeof p === 'function');
}
if (!isValidPrototype(proto)) throw new Error('bad prototype: ' + typeof proto);
var obj = Object.create(proto);

function isPrototypeOrNull(p) {
  return p === null || typeof p === 'object' || typeof p === 'function';
}

When it happens

Trigger: Calling Object.create with a non-object, non-null first argument: Object.create('foo'), Object.create(42), Object.create(undefined), Object.create(false). Often happens when a variable expected to hold a prototype object is actually a string/number (e.g. reading a config value or a JSON-parsed value that came back as a scalar).

Common situations: Passing a class name or constructor name string instead of the constructor's .prototype; passing undefined because a lookup returned nothing; old browsers (IE8) where the shim is active and library code assumed an object was present.

Related errors

• Object.defineProperty called on non-object: {object}
• Property description must be an object: {descriptor}
• can't convert {o} to object
• {fun} is not a function
• reduce of empty array with no initial value

AI-assisted analysis of dianping/cat@e815e74d4c (2026-08-14). Data as JSON: /api/errors/adff23f72262e358. Report an issue: GitHub.