Скачать или смотреть How to Dynamically Show a div Based on Checkbox Selections in Angular Material

Learn how to conditionally display specific ` div ` elements based on selected checkboxes in Angular Material. This guide provides an easy-to-understand walkthrough with practical examples.
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How to Dynamically Show a <div> Based on Checkbox Selections in Angular Material: A Step-by-Step Guide

When developing applications with Angular Material, you might encounter a scenario where the visibility of certain elements on the user interface depends on user selections, such as checkbox states in a stepper component. In this guide, we'll walk through how to conditionally show specific <div> elements when checkboxes are checked off.

The Problem

Imagine you have an Angular Material Stepper that includes a list of checkboxes. Each checkbox corresponds to an item. When a user checks off an item – for example, "Banana" – you want a specific <div> related to that item to appear in the next step of the stepper. So, if the user checks "Apple," a different <div> related to "Apple" should show up.

This might seem tricky, especially if you're new to coding. But fear not! We'll break down the solution into manageable steps.

The Solution

To achieve this, we need to leverage Angular's two-way data binding and directives effectively. Let's start with the foundational understanding of how Angular connects the model and the view.

Step 1: Setup Your Checkboxes

First, let's create our checkboxes within the first <mat-step>. We will use Angular's [(ngModel)] for bidirectional binding.

Here's how your checkbox could look:

[[See Video to Reveal this Text or Code Snippet]]

This means that when the checkbox is checked, the item.checked variable in your component will be set to true, and when unchecked, it will be set to false.

Step 2: Modify Your Item Structure

To utilize this efficiently, your array of items should look like this:

[[See Video to Reveal this Text or Code Snippet]]

This structure will allow you to know which item has been checked by its checked property.

Step 3: Create a Function to Check Selections

Next, you'll want a function that checks whether a specific item has been selected. Here’s a simple function you can use:

[[See Video to Reveal this Text or Code Snippet]]

The function will return true if the item is checked.

Step 4: Use Angular's *ngIf Directive for Conditional Rendering

Now that we can check which item is selected, we can conditionally display corresponding <div> elements like this:

[[See Video to Reveal this Text or Code Snippet]]

This way, only the <div> related to the checked item will be displayed.

Step 5: Optimize with a Getter or Event

If you want to keep your component clean, consider using a getter:

[[See Video to Reveal this Text or Code Snippet]]

And then in your HTML, you can simply utilize:

[[See Video to Reveal this Text or Code Snippet]]

Alternatively, you may want to update the visibility based on events. You can use:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By following these steps, you can create a feature-rich Angular Material Stepper that responds to user inputs dynamically. The combination of two-way data binding and Angular directives provides a clean and effective way to manage conditional display logic.

No matter your coding experience, breaking down problems into smaller chunks can help simplify the development process. So, whether you're new to Angular or looking to sharpen your skills, these techniques are essential for developing responsive and interactive applications.

Now, go ahead and implement this in your project to make it come alive!