js-learning-object-explicitly-property.js

    it("why need to set prototype property explicitly?", function() {
        //define object
        function Talent(name, category, majorTalent) {
            this.name = name || "";
            this.category = category || "unknown";
            this.majorTalent = majorTalent || "none";
        }

        function TalentedForMusic(name, category, majorTalent, skills) {
            //base is not special property. Assign the constructor of Talent to base.
            this.base = Talent;
            this.base(name, category, majorTalent);
            this.skills = skills || [];
        }
        
        function TalentedForPaint(name, category, majorTalent, skills) {
            //base is not special property. Assign the constructor of Talent to base.
            this.base = Talent;
            this.base(name, category, majorTalent);
            this.skills = skills || [];
        }
        TalentedForPaint.prototype = new Talent;

      
        //create instances
        var talented = new Talent("thinkhard.j.park", "engineering", "programming");
        expect(talented.name).toBe("thinkhard.j.park");
        expect(talented.category).toBe("engineering");
        expect(talented.majorTalent).toBe("programming");
        
        var hummingMan = new TalentedForMusic("humming man", "artist", "music", [""]);
        expect(hummingMan.name).toBe("humming man");
        expect(hummingMan.category).toBe("artist");
        expect(hummingMan.majorTalent).toBe("music");
        expect(hummingMan.skills).toBeDefined();
        
        var paintingGirl = new TalentedForPaint("painting girl", "artist", "art", [""]);
        expect(paintingGirl.name).toBe("painting girl");
        expect(paintingGirl.category).toBe("artist");
        expect(paintingGirl.majorTalent).toBe("art");
        expect(paintingGirl.skills).toBeDefined();

        Talent.prototype.grade = "none";
        expect(talented.grade).toBe("none");
        expect(hummingMan.grade).toBe(undefined);
        expect(paintingGirl.grade).toBe("none");
    });