What is Structure Directives in Angular with examples and types

Hello Guys,

In this blog we are going to learn about structure directive in angular with detail understanding and examples.

What is a Structure Directive in Angular?

Angular boasts a distinctive type of directive, known as the structure directive, that is purposed to change a webpage's DOM.

Such directives abound in the ability to add, remove or manipulate elements contingent on certain given conditions. Notably, these directives differ from attribute directives, which are known to primarily affect the behavior and appearance of an element, without manipulating it structurally.

Structure directives are therefore capable of removing, or adding elements to the webpage's DOM.

Angular has three directives for built-in structure: *ngIf, *ngFor, and *ngSwitch.

Here, we'll inspect each of them more closely.

*ngIf

Rendered elements in the DOM only if the *ngIf directive is utilized for conditional purposes.

The directive will analyze an expression and only display the element when the expression evaluates to true.

In the event that a button is meant to be shown solely when a user has logged in, the *ngIf directive can be applied in the following way:

This will render the button only if the showUserName variable is true.

*ngFor

The ngFor directive is used to loop through a collection of objects and create an object for each object.

For example,

if we have an array of users, we can use the *ngFor statement like this:

This will render a list item for each user in the users array, displaying their first name.

* ngSwitch

Instructions *ngSwitch is used to activate item by value.

Evaluates an expression and compares the result with a set of values. If a match is found, the relevant content is processed.

For example,

if we have a different color that can have three values: "pink", "green" or "blue", we can use the *ngSwitch directive like this:

This will make the Element color. If the color is "green", the first div will be displayed.

If the color is "pink" the second div is shown and so on. If the color does not match any of the specified values, the status will be displayed.

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