passing $scope object to a function in AngularJS

Question

I asked yesterday a similar question yet there is a difference. I'm trying to create a generic function that will change a scope object(not primitive) yet it seems not to be working and I don't understand why?

My code:

webApp.controller ('VotesCtrl', function ($scope) {
    $scope.param = {name: 'Ron', age: 18};        

    change($scope.param);

    function change(contextParam) {
      contextParam = {name:'dan', age: 12};
    }
});

It seems change function does not make any change on $scope.param even though I'm passing a reference.

When I'm doing the change like the code below, it is working!

webApp.controller ('VotesCtrl', function ($scope) {
    $scope.param = {name: 'Ron', age: 18};

    change($scope.param);

    function change(contextParam) {
      contextParam.name = 'dan';
      contextParam.age = 12;
    }
});

What am I doing wrong? how can you explain this behavior?

My Plunk

mingos · Accepted Answer · 2014-03-20 09:02:08Z

0

contectParam is a reference to an object. When you use the assign operator =, you change the value of the contextParam variable - it stops being a reference to an object and takes a completely different value.

However, when you access the properties of the object referenced by contextParam, you change their values, thus making your changes be visible outside the function's scope.

As a side note, it would be much better if you did things this way:

function change() {
    return {name: 'dan', age: 12};
}
$scope.param = change();

answered Mar 20, 2014 at 9:02

mingos

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1 Comment

Canttouchit Over a year ago

Thanks for the answer, another option is to use $.extend(true, configContext, {name:'dan', age: 12})

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