Data Binding
To better understand how Angular works, it's crucial to dive into one of its most important concepts - Data Binding. Data binding is a process that allows an internet user to manipulate web page elements using a web browser. It involves the synchronization of data between the model (or customer logic) and the view.
What is Data Binding?
In Angular, data binding is the automatic synchronization of data between the model (or business logic) and view components. It's a way to define the communication between the component and DOM. With data binding, you can control DOM elements or attributes using component data.
Types of Data Binding in Angular
Angular offers four forms of data binding, which are categorized based on how data flows.
Interpolation: This is a special syntax that Angular converts into a property binding. It’s a way to display data from a component on the view. The data is passed from the component to the specified HTML element inside double curly braces,
{{ }}.Property Binding: This type of data binding is used to set a property of a view element. Property binding uses the square brackets syntax,
[ ], to bind a DOM property to a component’s property.Event Binding: This type of binding lets your application respond to user input in the target environment by updating your application's data. Event binding uses the round brackets syntax,
( ).Two-way Binding: It is used to bind the model data to the form inputs or other elements, thereby making the model data update whenever the form input or element changes and vice versa. Angular uses a combination of square and round brackets syntax,
[( )], to achieve this.
Understanding Interpolation
Interpolation is one-way data binding, meaning data is exported from TypeScript code to HTML template. The interpolation binding is always enclosed in double curly braces like {{data}}. An example of interpolation in Angular could look like this:
<p>My name is {{name}}</p>
In this case, name is a property defined in the component’s class.
Understanding Property Binding
Property binding is another form of one-way data binding where we bind a property of a DOM element (like input, div, etc.) to a field which is a defined property in our component class. Property binding is done through square brackets []. Here is an example:
<input [value]='name'>
In this example, value is a property of the input box and name is a property of the component’s class.
Understanding Event Binding
Event binding is used to handle the events raised from the DOM like button click, mouse move, keystrokes, etc. When an event is fired, data flows from the DOM to the component. Here is an example of a button click event:
<button (click)='changeName()'>Change Name</button>
In this case, when the button is clicked, the changeName() function of the component’s class is called.
Understanding Two-way Binding
Two-way data binding means that UI fields are bound to model data dynamically such that when a UI field changes, the model data changes with it and vice versa. Two-way binding in Angular is achieved using a combination of event and property binding. Angular provides a specific syntax for this: [( )]. Here is an example of two-way binding:
<input [(ngModel)]='name'>
In this case, ngModel directive is used to implement two-way data binding.
Conclusion
Data binding is a core concept in Angular, and understanding it is crucial to becoming a proficient Angular developer. It helps to maintain synchronization between the model and view. By mastering the concept of data binding, you can build dynamic and interactive web applications using Angular.