(function(global) {
    function DetectorBase(configs) {
        if (!this instanceof DetectorBase) {
            throw new Error('Do not invoke without new.');
        }
        this.configs = configs;
        this.analyze();
    }

    DetectorBase.prototype.detect = function() {
        throw new Error('Not implemented');
    };

    DetectorBase.prototype.analyze = function() {
        console.log('analyze...');
        this.data = "###data###";
    };

    function LinkDetector(links) {
        DetectorBase.apply(this, arguments);
        if (!this instanceof LinkDetector) {
            throw new Error('Do not invoke without new.');
        }
        this.links = links;
    }

    function ContainerDetector(containers) {
        DetectorBase.apply(this, arguments);
        if (!this instanceof ContainerDetector) {
            throw new Error('Do not invoke without new.');
        }
        this.containers = containers;
    }

    // inherit first
    inherit(LinkDetector, DetectorBase);
    inherit(ContainerDetector, DetectorBase);

    // expand later
    LinkDetector.prototype.detect = function() {
        console.log('Loading data:' + this.data);
        console.log('link detection started.');
        console.log('Scaning links:' + this.links);
    };

    ContainerDetector.prototype.detect = function() {
        console.log('Loading data:' + this.data);
        console.log('link detection started.');
        console.log('Scaning containers:' + this.containers);
    };

    // prevent from being altered
    Object.freeze(DetectorBase);
    Object.freeze(DetectorBase.prototype);
    Object.freeze(LinkDetector);
    Object.freeze(LinkDetector.prototype);
    Object.freeze(ContainerDetector);
    Object.freeze(ContainerDetector.prototype);

    // export to global object
    Object.defineProperties(global, {
        LinkDetector: { value: LinkDetector },
        ContainerDetector: { value: ContainerDetector },
        DetectorBase: { value: DetectorBase }
    });

    function inherit(subClass, superClass) {
        subClass.prototype = Object.create(superClass.prototype);
        subClass.prototype.constructor = subClass;
    }
}(this));

var containerDetector = new ContainerDetector('#nav #banner #sidebar');
containerDetector.detect();

var linkDetector = new LinkDetector('https://www.alipay.com https://www.aliyun.com');
linkDetector.detect();