Understanding NestJS and Handlebars

Oct 13, 2025 by pynkocean.com 0 views

Introduction

When building a web application using NestJS for the backend and Handlebars (hbs) for templating, it's essential to understand how to link your JavaScript code to your Handlebars file. In this article, we'll explore the process of integrating your JavaScript code with your Handlebars template in NestJS.

Understanding NestJS and Handlebars

NestJS

NestJS is a progressive Node.js framework for building efficient, scalable Node.js server-side applications. It provides a robust set of features for building robust and maintainable applications. NestJS is built on top of TypeScript and uses the Express.js framework under the hood.

Handlebars

Handlebars is a templating engine that allows you to separate presentation logic from application logic. It's a popular choice for building web applications, especially when working with Node.js. Handlebars provides a simple and intuitive way to render dynamic data in your templates.

Setting Up Your Project

To link your JavaScript code to your Handlebars file in NestJS, you'll need to set up your project first. Here's a step-by-step guide to get you started:

Step 1: Create a New NestJS Project

Create a new NestJS project using the following command:

npx @nestjs/cli new my-app

This will create a new NestJS project called my-app.

Step 2: Install Handlebars

Install the Handlebars package using the following command:

npm install handlebars

Step 3: Create a Handlebars Template

Create a new file called index.hbs in the src/views directory:

src/views
  index.hbs

This file will contain your Handlebars template.

Linking Your JavaScript Code to Your Handlebars File

Now that you have your project set up and your Handlebars template created, it's time to link your JavaScript code to your Handlebars file. Here's how you can do it:

Step 1: Create a Controller

Create a new controller called app.controller.ts in the src/app directory:

src/app
  app.controller.ts

This controller will handle requests to your application.

Step 2: Use the Handlebars Service

Use the Handlebars service to render your template:

import { Controller, Get, Render } from '@nestjs/common';
import { HandlebarsService } from './handlebars.service';
@Controller()
export class AppController 
constructor(private readonly handlebarsService HandlebarsService) {
@Get()
index(): Render 
const data = { name 'John Doe' ;
return this.handlebarsService.render('index', data);
}
}

In this example, we're using the HandlebarsService to render the index template with the data object.

Step 3: Create a Handlebars Service

Create a new service called handlebars.service.ts in the src/app directory:

src/app
  handlebars.service.ts

This service will handle Handlebars-related tasks.

Step 4: Use the Handlebars Template Engine

Use the Handlebars template engine to render your template:

import { Injectable } from '@nestjs/common';
import * as Handlebars from 'handlebars';
@Injectable()
export class HandlebarsService 
async render(template string, data: any): Promise<string> {
const templateString = await this.readFile(template);
const compiledTemplate = Handlebars.compile(templateString);
return compiledTemplate(data);

private async readFile(template: string): Promise<string> {
const filePath = src/views/${template};
const fileContent = await import(../views/${template});
return fileContent.default;
}
}

In this example, we're using the Handlebars template engine to compile and render the index template with the data object.

Conclusion

Linking your JavaScript code to your Handlebars file in NestJS is a straightforward process. By following the steps outlined in this article, you can integrate your JavaScript code with your Handlebars template and build robust and maintainable web applications.

Additional Resources

Example Use Cases

Building a data collection app using NestJS for the backend and Handlebars (hbs) for templating.
Creating a web application that allows users to submit personal information via a form without requiring registration.
Building a robust and maintainable web application using NestJS and Handlebars.

Code Snippets

app.controller.ts:

import { Controller, Get, Render } from '@nestjs/common';
import { HandlebarsService } from './handlebars.service';
@Controller()
export class AppController 
constructor(private readonly handlebarsService HandlebarsService) {
@Get()
index(): Render 
const data = { name 'John Doe' ;
return this.handlebarsService.render('index', data);
}
}

handlebars.service.ts:

import { Injectable } from '@nestjs/common';
import * as Handlebars from 'handlebars';
@Injectable()
export class HandlebarsService 
async render(template string, data: any): Promise<string> {
const templateString = await this.readFile(template);
const compiledTemplate = Handlebars.compile(templateString);
return compiledTemplate(data);

private async readFile(template: string): Promise<string> {
const filePath = src/views/${template};
const fileContent = await import(../views/${template});
return fileContent.default;
}
}

index.hbs:

<h1>Hello, {{ name }}!</h1>

Q: What is the purpose of using Handlebars in NestJS?

A: Handlebars is a templating engine that allows you to separate presentation logic from application logic. It's a popular choice for building web applications, especially when working with Node.js. By using Handlebars in NestJS, you can render dynamic data in your templates and create robust and maintainable web applications.

Q: How do I install Handlebars in my NestJS project?

A: To install Handlebars in your NestJS project, run the following command:

npm install handlebars

Q: What is the difference between a Handlebars template and a JavaScript file?

A: A Handlebars template is a file that contains a template written in Handlebars syntax. It's used to render dynamic data in your application. A JavaScript file, on the other hand, contains code that's executed by the browser or Node.js. While both files are used in web development, they serve different purposes.

Q: How do I link my JavaScript code to my Handlebars file in NestJS?

A: To link your JavaScript code to your Handlebars file in NestJS, you'll need to create a controller that uses the Handlebars service to render your template. Here's an example:

import { Controller, Get, Render } from '@nestjs/common';
import { HandlebarsService } from './handlebars.service';
@Controller()
export class AppController 
constructor(private readonly handlebarsService HandlebarsService) {
@Get()
index(): Render 
const data = { name 'John Doe' ;
return this.handlebarsService.render('index', data);
}
}

Q: What is the purpose of the Handlebars service in NestJS?

A: The Handlebars service is responsible for rendering Handlebars templates in your application. It provides a way to separate presentation logic from application logic and makes it easier to maintain and update your templates.

Q: How do I use the Handlebars service in my controller?

A: To use the Handlebars service in your controller, you'll need to inject it into your controller class. Here's an example:

import { Controller, Get, Render } from '@nestjs/common';
import { HandlebarsService } from './handlebars.service';
@Controller()
export class AppController 
constructor(private readonly handlebarsService HandlebarsService) {
@Get()
index(): Render 
const data = { name 'John Doe' ;
return this.handlebarsService.render('index', data);
}
}

Q: What is the difference between `render` and `compile` in the Handlebars service?

A: render is used to render a Handlebars template with dynamic data, while compile is used to compile a Handlebars template into a JavaScript function. render is typically used in controllers, while compile is used in services or other parts of your application.

Q: How do I handle errors in my Handlebars templates?

A: To handle errors in your Handlebars templates, you can use the try/catch block in your controller or service. Here's an example:

import { Controller, Get, Render } from '@nestjs/common';
import { HandlebarsService } from './handlebars.service';
@Controller()
export class AppController 
constructor(private readonly handlebarsService HandlebarsService) {
@Get()
index(): Render 
try {
const data = { name 'John Doe' ;
return this.handlebarsService.render('index', data);
} catch (error) {
console.error(error);
return 'Error rendering template';
}
}
}

Q: Can I use Handlebars with other templating engines in NestJS?

A: Yes, you can use Handlebars with other templating engines in NestJS. However, you'll need to create a custom service that uses the other templating engine and inject it into your controller or service.

Q: How do I optimize my Handlebars templates for performance?

A: To optimize your Handlebars templates for performance, you can use the following techniques:

Use caching to store compiled templates
Use a template engine that supports caching, such as Handlebars
Minify and compress your templates
Use a build tool, such as Webpack, to optimize your templates

Note: This is a basic Q&A article and you may need to modify it to fit your specific use case.