Using a JavaScript variable within an AngularJS scope

Question

Using a JavaScript variable within an AngularJS scope

Currently in the process of building a webpage with the MEAN stack, I utilized the HTML5/Javascript sessionStorage variable to store the user data for access across all pages.

Now, the challenge is passing this data into angularJS through the controller without requiring the user to input the value again. Attempts to set the username field as readonly and assign the value using getElementByID were unsuccessful, as angularJS continued to retrieve the old value of "". This occurred because the initial text field value was empty, resulting in an undefined user in the angularJS scope.

Another strategy was to pass the value as a hidden scope, but this approach also failed due to angular's constraints.

Is there a simpler method to declare the variable within ng-model? The underlying issue is that any ng value assumes "", interpreting "user" solely as the text "user" rather than a variable.

Any assistance on this matter would be greatly valued.

javascript angularjs

Answer 1

Answer №1

To store your username in sessionStorage, simply use the following code:

window.sessionStorage.setItem("username","toby");

In an Angular controller, you can access the stored username like this:

$scope.username = window.sessionStorage.getItem("username");

(Note: this method will not automatically update the username in the session storage)

Remember, if you need to store JSON data in session or local storage, you should stringify it first:

window.sessionStorage.setItem("userObject", JSON.stringify(userObject));

To retrieve the JSON data, use:

var userObject = JSON.parse(window.sessionStorage.getItem("userObject"));

If you want to monitor changes in session storage, you can use the $watch function:

$scope.$watch(
    function(){return window.sessionStorage.getItem("username");},
    function(newVal, oldVal){
        console.log("Username changed from", oldVal, "to", newVal);
    }
);

Answer 2

To store your username in sessionStorage, simply use the following code:

window.sessionStorage.setItem("username","toby");

In an Angular controller, you can access the stored username like this:

$scope.username = window.sessionStorage.getItem("username");

(Note: this method will not automatically update the username in the session storage)

Remember, if you need to store JSON data in session or local storage, you should stringify it first:

window.sessionStorage.setItem("userObject", JSON.stringify(userObject));

To retrieve the JSON data, use:

var userObject = JSON.parse(window.sessionStorage.getItem("userObject"));

If you want to monitor changes in session storage, you can use the $watch function:

$scope.$watch(
    function(){return window.sessionStorage.getItem("username");},
    function(newVal, oldVal){
        console.log("Username changed from", oldVal, "to", newVal);
    }
);

Answer 3

Answer №2

If you find that AngularJS is not responding to an updated value, consider using the $apply() function. You can learn more about it in this helpful article on $apply(). Remember to call $apply() when you make changes to the model that Angular is not aware of, such as outside of an $http call. Make sure to wrap your function inside the $apply() call, like this:

$scope.$apply(function(var) {
    etc.
}

In addition, if you want to assign a value in a controller to the model, you'll need to declare a model variable inside the controller if you're using an MVC framework. For instance, your controller may start with:

.controller("exampleCtrl", function($scope) {
    $scope.model = model;
}

Then, you can update a value in the model by using:

$scope.model.VALUENAME = whatever value

I hope this information is useful for you!

Answer 4

If you find that AngularJS is not responding to an updated value, consider using the $apply() function. You can learn more about it in this helpful article on $apply(). Remember to call $apply() when you make changes to the model that Angular is not aware of, such as outside of an $http call. Make sure to wrap your function inside the $apply() call, like this:

$scope.$apply(function(var) {
    etc.
}

In addition, if you want to assign a value in a controller to the model, you'll need to declare a model variable inside the controller if you're using an MVC framework. For instance, your controller may start with:

.controller("exampleCtrl", function($scope) {
    $scope.model = model;
}

Then, you can update a value in the model by using:

$scope.model.VALUENAME = whatever value

I hope this information is useful for you!

Answer 5

Answer №3

This solution worked in my case:

// Within the JavaScript section, invoke an Angular method to update the data upon clicking, changing, etc.

angular.element(document.getElementById('YourElementId')).scope().update_your_data();

Additionally,

// Within the Angular controller

$scope.update_your_data =  function(){
    $scope.your_data.value        = $('#YourElementId').val(); //  or document.getElementById('YourElementId')).value
    $scope.$apply();
}

Answer 6

This solution worked in my case:

// Within the JavaScript section, invoke an Angular method to update the data upon clicking, changing, etc.

angular.element(document.getElementById('YourElementId')).scope().update_your_data();

Additionally,

// Within the Angular controller

$scope.update_your_data =  function(){
    $scope.your_data.value        = $('#YourElementId').val(); //  or document.getElementById('YourElementId')).value
    $scope.$apply();
}

Using a JavaScript variable within an AngularJS scope

Answer №1

Answer №2

Answer №3

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