JavaScript: Empty Object Comparison
Blogs20132013-09-09
JavaScript: Empty Object Comparison
The following is my summary of empty object comparsion. They used in node command line. They are slightly difference. For prototype inheritance, always use var o={};
| var o; //undefined | var o=null; //for empty object | var o={}; //distinct a object |
|---|---|---|
| var o; | var o=null; | var o = {}; |
| o.__proto__; //Error | o.__proto__; //Error | o.__proto__; // {} |
| o.constructor; //Error | o.constructor; //Error | o.constructor; // [Function: Object] |
| o.instanceof Object; //false | o.instanceof Object; //false; | o instanceof Object; // true |
| typeof o; //āundefinedā | typeof t; //āobjectā | typeof o; // āobjectā |
| o; //undefined | o; //null | o; //{} |
| o.length; // Error | o.length; //Error | o.length; //undefined |
| o.toString(); //Error | o.toString(); //Error | o.toString(); //[object Object] |