javascript - angularjs $watch cannot detect change of Property in an object -

i'm setting watch $scope object not trigger $watch change event unless whole value changed

example :

//some in .run function set rootscope , set $watch too. $rootscope.config = {date:'11/4/2015',morevalues:'etc'};  //setting $watch $rootscope.$watch('config',function(new,old) { console.log('config value changed :)',new); });  //----->inside controller----------  //now not trigger $watch $rootscope.config.date = 'another day';  //same this, not trigger $watch var temp = $rootscope.config; temp.date = 'another day'; $rootscope.config = temp;  //yet work fine :) , trigger $watch var temp = angular.copy($rootscope.config); temp.date = 'another day'; $rootscope.config = temp; 

can tell me why behavior? there better way trigger $watch on change of object property?

you can use $watchcollection, or pass third param true

$rootscope.$watch('config',function(value,old) { console.log('config value changed :)',value); }, true); 

or

$rootscope.$watchcollection('config',function(value,old) { console.log('config value changed :)',value); }); 

• scope $watch() vs. $watchcollection() in angularjs