프로토타입 상속을 한 사용자 정의 객체를 사용할때는
typeof, instanceof, constructor 프로퍼티, toString() 메소드등의
도움을 얻어 판달할 필요가 있음.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 | var Parent = function(){};Parent.prototype.constructorname = 'Parent';var Child = function(){};Child.prototype = new Parent();Child.prototype.constructor = Child;Child.prototype.constructorname = 'Child';var child = new Child();document.writeln('typeof Parent : ' + typeof Parent + '');document.writeln('typeof Child : ' + typeof Child + '');document.writeln('typeof child : ' + typeof child + '');/* return: typeof Parent : function typeof Child : function typeof child : object * */document.writeln('child instancdof Object : ' + ( child instanceof Object) + '');document.writeln('child instancdof Parent : ' + ( child instanceof Parent) + '');document.writeln('child instancdof Child : ' + ( child instanceof Child) + '');/* return: child instancdof Object : true child instancdof Parent : true child instancdof Child : true * */document.writeln('child.constructor === Object: ' + ( child.constructor === Child) + '');document.writeln('child.constructor === Parent: ' + ( child.constructor === Parent) + '');document.writeln('child.constructor === Child: ' + ( child.constructor === Child) + '');/* return: child.constructor === Object: true child.constructor === Parent: false child.constructor === Child: true * */function checkType(obj){ // null일 경우 문자열 'null' 반환 if(obj === null){ return 'null'; } //typeof가 'object'가 아닐경우 type반환 var type = typeof obj; if(type != 'object'){ return type; } //obj.toString()의 결과를 저장 var str = Object.prototype.toString.call(obj); // 생성자 이름 추출 var constructor = str.substring(8, str.length - 1); if(constructor != 'Object'){ return constructor; } if(obj.constructor == 'Object'){ return constructor; } // 사용자 정의 객체의 생성자 함수의 프로토타입 객체에 정의해 놓은 constructorname // 프로퍼티가 있으면 constructorname을 반환 if('constructorname' in obj.constructor.prototype) return obj.constructor.prototype.constructorname; return '객체의 타입을 알수 없습니다.';}document.writeln('checkType(child) : ' + checkType(child) + '');/* return: checkType(child) : Child * */ |
