How To Have A Default Option In The Angular JS Select Box

The select box is an important HTML element for creating dropdown menus. In AngularJS, managing a default option in a select box can be seamlessly acquired by using the framework’s data-binding capabilities. This article will help you know the step-by-step process of implementing a default option using AngularJS in the select box.

Table of Contents

• Introduction to Select Box and Default Option
  • Select Box in AngularJS?
  • Default Option in Angular JS Select Box?
• Setting up Default Option in the AngularJS Select Box
  • Setting Up a Select Box in AngularJS
    • HTML Structure for a Basic Select Box
    • Adding Data Using ng-options
  • Implementing a Default Option
    • Using ng-model for Default Value Binding
    • Specifying a Placeholder or Static Option
  • Handling Dynamic Data for Default Options
• Conclusion
• FAQs

Introduction to Select Box and Default Option

Select Box in AngularJS?

A Select Box is a dropdown menu in which one value can be chosen from a predefined list. In AngularJS, it is easier to bind data to a select box using the ng-options directive for dynamic and efficient solutions.

Default Option in Angular JS Select Box?

A default option in the AngularJS select box refers to a pre-selected value for a better user experience by minimizing time and confusion when a user interacts with the forms.

Setting up Default Option in the AngularJS Select Box

Setting Up a Select Box in AngularJS

1. HTML Structure for a Basic Select Box

Here’s an example of a basic select box using AngularJS:

<div ng-app="myApp" ng-controller="myCtrl">
    <select ng-model="selectedItem" ng-options="item for item in items"></select>
</div>

Explanation: This example will create a dropdown using AngularJS. The ng-app set up the app and ng-controller sets the controller. The ng-model links the selected value to a variable, and ng-options will later add the options to the dropdown from the controller. Right now, the dropdown is empty and will fill with options later..

2. Adding Data Using ng-options

In the controller, define an array of items for the dropdown:

angular.module('mytApp', []).controller('myCtrl', function($scope) {
    $scope.items = ['Option 1', 'Option 2', 'Option 3'];
});

Explanation: In this part, the controller defines an array of options as Option 1, Option 2, Option 3. These options will be displayed in dropdown as choices to the user.

Implementing a Default Option

Case 1: Using ng-model for Default Value Binding

You can set the default option by pre-assigning a value to ng-model:

<div ng-app="myApp" ng-controller="myCtrl">
    <select ng-model="selectedItem" ng-options="item for item in items"></select>
</div>

In the controller:

$scope.selectedItem = 'Option 2'; // Default selected option

Explanation: When the page loads, Option 2 will be pre-selected.

Case 2: Specifying a Placeholder or Static Option

If you want a placeholder (e.g., “Select an option”), include a static <option>:

<div ng-app="myApp" ng-controller="myCtrl">

    <select ng-model="selectedItem">

        <option value="" disabled>Select an option</option>

        <option ng-repeat="item in items" value="{{item}}">{{item}}</option>

    </select>

</div>

Explanation: This code creates a dropdown with a default “Select an option” prompt.

Handling Dynamic Data for Default Options

Dynamic data is the that is loaded after the page has already loaded such as from an API or a database. In such a case, you need to make sure that the default value for a select box is set after the data is available because if you set the default value before the data is loaded, the ng-model might not correctly match any of the options because the options are still being loaded.

When the options are dynamically loaded, make sure that the default value is set after the data is available:

angular.module('myApp', []).controller('myCtrl', function($scope, $timeout) {

    $scope.items = [];

    // Simulate dynamic data loading

    $timeout(function() {

        $scope.items = ['Option A', 'Option B', 'Option C'];

        $scope.selectedItem = 'Option B'; // Set default value dynamically

    }, 1000);

});

Here, the default value (Option B) is assigned once the data is loaded.

Conclusion

​​It is easy to add a default option in an AngularJS select box using ng-model. You can make your dropdown menus more user-friendly by pre-assigning a value or including a static placeholder. However, when working with dynamic data, ensure proper synchronization between the data source and the ng-model value.

FAQs

select option[value=""] {

    color: gray;

}