不能保证以相同的方式序列化JSON对象，也不能保证属性以相同的顺序进行序列化，使用
JSON.stringify并不是测试对象相等性的好方法。
一个更好的例子是这样的函数（前一段时间在互联网上找到，希望我能感谢原始作者）
function equals ( x, y ) { // If both x and y are null or undefined and exactly the same if ( x === y ) { return true; } // If they are not strictly equal, they both need to be Objects if ( ! ( x instanceof Object ) || ! ( y instanceof Object ) ) { return false; } // They must have the exact same prototype chain, the closest we can do is // test the constructor. if ( x.constructor !== y.constructor ) { return false; } for ( var p in x ) { // Inherited properties were tested using x.constructor === y.constructor if ( x.hasOwnProperty( p ) ) { // Allows comparing x[ p ] and y[ p ] when set to undefined if ( ! y.hasOwnProperty( p ) ) { return false; } // If they have the same strict value or identity then they are equal if ( x[ p ] === y[ p ] ) { continue; } // Numbers, Strings, Functions, Booleans must be strictly equal if ( typeof( x[ p ] ) !== "object" ) { return false; } // Objects and Arrays must be tested recursively if ( !equals( x[ p ], y[ p ] ) ) { return false; } } } for ( p in y ) { // allows x[ p ] to be set to undefined if ( y.hasOwnProperty( p ) && ! x.hasOwnProperty( p ) ) { return false; } } return true;},
