问函数实例hasOwnProperty()混淆

EN

var base = (function () {

    var cls = function () { };

    cls.prototype.doStuff = function () {
        console.log('dostuff');
    };

    return cls;

})();

var child = (function () {

    var cls = function () {
        base.call(this);
    };

    cls.prototype = Object.create(base.prototype);
    cls.prototype.constructor = child;

    cls.prototype.doOtherStuff = function () { // <--
        console.log('doOtherStuff');
    }

    return cls;

})();

var b = new child();

console.log(b.hasOwnProperty('doOtherStuff'), 'doOtherStuff' in b); //false true