cmp = function( 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 ( ! Object.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; };

objA={  a:'123',  b:'456' }; objB={  a:'123',  b:'000' }; var isEqual= cmp(objA, objB);  console.log(isEqual);  // false 不相同