How to Programmatically Change routerLink in Angular and TypeScript

Learn how to easily modify `routerLink` in your Angular application by dynamically adding query string parameters using TypeScript.
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How to Programmatically Change routerLink in Angular and TypeScript

Introduction

When developing Angular applications, it's common to navigate between different routes using the routerLink directive. However, there might be scenarios where you need to add query string parameters to your route links programmatically. In this guide, we'll walk through how to modify routerLink to include query parameters using Angular and TypeScript, particularly in Angular 13.

The Problem

In a standard Angular component, you might have a navigation menu set up like this:

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

Imagine you want to add a query string parameter (e.g., pi=160016) to all these links, and you want to do this dynamically within the ngOnInit method of your component. How can you achieve this in a clean way without hardcoding the changes into your HTML?

The Solution

To dynamically modify the routerLink, we'll use Angular's powerful service pattern. We'll create a service to store and retrieve the query parameter that can then be passed along to each link.

Step 1: Create a Shared Service

The first step is to create a service that will hold the query string value. This service will allow us to set a value and retrieve it whenever needed.

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

Step 2: Set the Query String in Your Component

Now we will use this service in a child component to set the query parameter.

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

Step 3: Retrieve the Query String in Your Menu Component

Next, we will retrieve the query string in the component where you have defined the menu links and update the routerLink to use the dynamically set query parameter.

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

Step 4: Update the Menu Template

Finally, update your menu template to use the queryParams directive to append the query parameter dynamically:

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

Conclusion

By following these steps, you can programmatically add query string parameters to your routerLinks in Angular using a service for shared state. This approach not only keeps your code clean and organized but also allows for easy modifications in the future. Whether you're developing complex single-page applications or just enhancing user experience, implementing dynamic routing with query parameters is a valuable skill.

Feel free to reach out if you have any questions or need further assistance while working with Angular routing!