javascript - What is "=*" in AngularJS -

i've come across way of isolate binding specification:

scope: {    property: "=*" } 

what asterisk mean here? can please provide example?

the isolate binding =* shallow watch change in collection.

let me explain bit:

normally watchcollection variables use in scripts below:

$scope.arr = ['foo', 'bar', 'lorem', 'ipsum']; $scope.arrcount = 4;  $scope.$watchcollection('arr', function(new, old) {   $scope.arrcount = new.length; });  

but if want object binding in html attribute itself?

<my-directive my-attr="arr"><!--$scope.arr--> 

and, if this:

scope: {    myattr: "=*" } 

now, directive attributes assigned should shallow watch. , use of watchcollection of use time.

so, =* used when need shallow watch changes (i.e. $watchcollection instead of $watch) can use =* or =attr (=? or =*?attr if property optional) described in docs.

although, can use = watchcollection watch object or array can use =* same. difference using =* method collection becomes true , when collection becomes true angularjs use $watchcollection remove watcher , uses $watch remove watcher when collection false:

if (definition.collection) { //using `=*`   removewatch = scope.$watchcollection(attrs[attrname], parentvaluewatch); } else { //using `=`   removewatch = scope.$watch($parse(attrs[attrname],      parentvaluewatch), null, parentget.literal); } 

so, when want shallow watch collection need use =*.