Data Binding in Angular 2 Explained

Data binding is a core feature of modern web development frameworks that synchronizes the data displayed in the view with the model. Without data binding, developers would have to write code that constantly synchronizes the view with the model and vice versa. This can become a tedious task, especially as the application starts to grow.

Angular, a robust JavaScript framework, provides a powerful solution to this problem through its implementation of data binding. This article will delve into the concept of data binding in Angular, focusing on how Angular 2 handles this feature and how it differs from Angular 1.

Two-way Data Binding in Angular 1

One of the standout features of Angular 1 was its implementation of two-way data binding. In this system, any changes that occur in the model are propagated to the view, and any changes the user makes in the view are updated in the model. This eliminated a significant amount of code that developers would otherwise have to write to synchronize the view-model.

However, Angular 1’s implementation of two-way data binding raised some performance concerns. To keep the model-view in sync, Angular 1 used a concept called “dirty checking”. Any changes in the $scope properties or the DOM would trigger a digest cycle, which was responsible for keeping the view-model in sync. This approach had its limitations and could lead to performance issues in larger applications.

Data Binding in Angular 2

Angular 2 addressed the performance concerns of Angular 1 by setting a clear authority of the data. Data binding in Angular 2 can be broadly classified into two types: Event Binding and Property Binding.

Event Binding is used when the user interacts with the application, such as clicking on an element or typing something. Property Binding, on the other hand, is used to reflect changes in the model directly into the DOM.

Angular 2 does not provide a direct mechanism to implement two-way data binding. However, it can still be achieved by combining event and property binding on the same element. This combination of event and property binding is often referred to as “Box of Bananas”.

How is Angular 2 Different from Angular 1?

The key difference between Angular 1 and Angular 2’s approach to data binding lies in the authority of the data. In Angular 2, the model has clear authority over the data. This means that whatever is in the model is considered truth, and the DOM is just a replica of the model.

So, a change in the model will reflect in the DOM. But if there is a change in the DOM (by a user interaction), the data is propagated to the model via the event, thereby updating the model and thus the DOM. This approach gives a significant performance advantage to Angular 2 over Angular 1.


Data binding is a crucial aspect of modern web development, and understanding how it works in Angular can help developers build more efficient and interactive web applications. By setting a clear authority of the data and combining event and property binding, Angular 2 provides a powerful and efficient solution for data binding.


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