What is ngIf directive in Angular? How to use ngIf directive in Angualr?

 ngIf is a built-in directive in Angular that allows you to conditionally render or remove an HTML element based on the value of an expression in your component.

The ngIf directive takes an expression as its value, which should evaluate to a boolean. If the expression is true, the element is rendered. If the expression is false, the element is removed from the DOM.

Here's an example:

html
<div *ngIf="isShown">Hello World!</div>

In this example, the ngIf directive is used to conditionally render a div element based on the value of the isShown expression in the component's class. If isShown is true, the div element will be displayed. If isShown is false, the div element will be removed from the DOM.

You can also use the ngIf directive with an else clause to conditionally render an alternate element when the expression is false. For example:

html
<div *ngIf="isShown; else notShown">Hello World!</div>
<ng-template #notShown><p>This element is shown when isShown is false</p></ng-template>

In this example, the else clause is used to render a p element when the isShown expression is false. The #notShown template reference variable is used to define the alternate element.

The ngIf directive can be useful for conditionally rendering elements based on user interactions, form values, or other state changes in your application. It is a powerful tool for creating dynamic and responsive user interfaces.