What is the principle of two-way data binding?

The principle of two-way data binding is mainly realized through the observer mode, data hijacking, publish/subscribe mode and data monitoring. In traditional development, data updates are usually realized by manually operating DOM elements. , and two-way data binding can automatically reflect data changes to the view, and can also automatically update the data model when the input in the view changes.

#Two-way data binding is a mechanism to achieve synchronous updates between the data model and the view. In traditional development, data updates are usually achieved by manually manipulating DOM elements, while two-way data binding can automatically reflect data changes to the view, and can also automatically update the data when the input in the view changes. Model.

The principle of realizing two-way data binding mainly relies on the following aspects:

Observer pattern: The implementation of two-way data binding is inseparable from the observer pattern. In this pattern, there is a relationship between an observed object (the data model) and multiple observers (the views). When the status of the observed changes, all observers will be notified to perform corresponding update operations.

Data hijacking: In order to automatically update the data model changes to the view, two-way data binding usually uses data hijacking. Data hijacking is hijacking the read and set operations of properties of the data model by using the Object.defineProperty() method. In this way, when the value of the attribute changes, the corresponding update operation can be triggered.

Publish/subscribe mode: In the implementation of two-way data binding, the publish/subscribe mode also plays an important role. In this pattern, there is a relationship between a publisher (data model) and multiple subscribers (views). When the status of the publisher changes, all subscribers will be notified to perform corresponding update operations.

Data monitoring: In order to automatically update input changes in the view to the data model, two-way data binding is usually implemented by listening to events in the view. For example, you can listen to the input event of the input element. When the input changes, you can get the latest value and update it to the data model.

To sum up, the principle of two-way data binding is mainly realized through the observer mode, data hijacking, publish/subscribe mode and data monitoring. When the status of the data model changes, all observers will be notified to perform corresponding update operations; when the input in the view changes, the latest value will be updated to the data model. Through this mechanism, synchronous updates between the data model and the view can be achieved, improving development efficiency and user experience.

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