ng-content vs ng-templatevs ng-container in angualr

 In Angular, ng-content, ng-template, and ng-container are all structural or content projection elements that help manage the rendering and composition of the DOM. Each serves a different purpose:

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🔹 1. ng-content

✅ Use case: Content projection (used in Angular component design)

It allows you to project external content into a component’s template. Think of it as a placeholder where parent content will be inserted.

📌 Example:

<!-- parent.component.html -->
<app-child>
  <p>This content will be projected</p>
</app-child>

<!-- child.component.html -->
<ng-content></ng-content>

🧠 Key Points:

• Use in custom reusable components.
• Supports multiple slots using select:

<ng-content select="header"></ng-content>
<ng-content select="footer"></ng-content>

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🔹 2. ng-template

✅ Use case: Define template fragments that are not rendered immediately but can be used later (conditionally or via *ngIf, ngTemplateOutlet, etc.).

📌 Example:

<ng-template #loading>
  <p>Loading...</p>
</ng-template>

<div *ngIf="isLoading; else content">
  <ng-container *ngTemplateOutlet="loading"></ng-container>
</div>

<ng-template #content>
  <p>Data loaded!</p>
</ng-template>

🧠 Key Points:

• Not part of the DOM until explicitly rendered.
• Useful in conditional rendering, ngIf else, or reusable templates.

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🔹 3. ng-container

✅ Use case: A logical container without rendering any additional DOM element.

📌 Example:

<ng-container *ngIf="isAdmin">
  <button>Edit</button>
  <button>Delete</button>
</ng-container>

🧠 Key Points:

• Does not render to DOM (i.e., no <div> or wrapper).
• Useful for grouping structural directives (like *ngIf, *ngFor) without introducing extra markup.

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🧾 Summary Table:

Feature	ng-content	ng-template	ng-container
Purpose	Content projection	Define template fragments	Group DOM logically
Renders HTML?	Yes (with projected content)	No (until explicitly used)	No
DOM Element?	Yes (placeholder)	No	No
Common Uses	Custom component design	*ngIf else, ngTemplateOutlet	Conditional rendering block