Template Variable

In Angular, a template variable is a reference to a DOM element or directive within a template. It is denoted by a hash symbol (#) followed by a variable name. For example, you could define a template variable for an input element like this:

<input #inputElement>

Once the variable is defined, you can use it to access the DOM element or directive from within the component class. For example, you might use it to set focus on the input element:

@ViewChild('inputElement') inputElement: ElementRef;

setFocus() {
  this.inputElement.nativeElement.focus();
}

You can also use template variables to bind to the value of a DOM element or directive, or to bind to an event emitted by the element or directive.

<input #inputElement (input)="onInput(inputElement.value)">

In this example, the template variable inputElement is used to bind to the input event emitted by the input element. The onInput() method in the component class will be called with the current value of the input element each time the input event is emitted.

There are several situations where you might use template variables in Angular:

  1. To access a DOM element or directive from within the component class: As mentioned earlier, you can use a template variable to reference a DOM element or directive, and then use it to access the element or directive from within the component class. This can be useful if you need to perform some operation on the element, such as setting focus or modifying its style.
  2. To bind to the value of a DOM element or directive: You can use a template variable to bind to the value of a DOM element or directive, such as an input element. This can be useful if you need to use the value of the element in some way, such as sending it to a server or storing it in a component property.
  3. To bind to an event emitted by a DOM element or directive: You can use a template variable to bind to an event emitted by a DOM element or directive, such as a button element. This can be useful if you need to perform some action in response to the event, such as updating a component property or displaying a message.
  4. To pass a template reference variable to a directive: You can use a template variable to pass a reference to a DOM element or directive to a directive. This can be useful if the directive needs to perform some operation on the element or directive, such as setting focus or modifying its style.

Overall, template variables are a powerful tool that can help you create more interactive and dynamic templates in your Angular app.