Building Serverless Frontend Applications

The core of front-end applications using Serverless architecture lies in static resource hosting and back-end on-demand calls. The key points include: 1. Deploy static resources to CDN, automatically build and deploy through AWS S3, Vercel, Netlify and other platforms, and reasonably configure cache policies; 2. Back-end functions are implemented by cloud functions, such as AWS Lambda and Cloudflare Workers, which handle database access, email sending, image cropping and other tasks, and trigger the return of JSON data with HTTP requests; 3. Use Serverless databases such as Supabase, DynamoDB, PlanetScale and other Serverless databases or low-code solutions to manage data, and directly call them through API or SDK, eliminating the intermediate layer construction; 4. Pay attention to security and performance details, such as permission control and API Key management, cold start optimization and cross-domain problem handling to ensure the stable and efficient operation of the system.

In fact, it is not a new concept to use the Serverless architecture for front-end applications. It mainly refers to deploying the front-end on a CDN, and the back-end logic is implemented through cloud functions (such as AWS Lambda and Cloudflare Workers), saving server maintenance costs. The core is: static resource hosting backend calls on demand.

The following points are the most critical parts in actual operation:

1. Deploy static resources to CDN

The first step in the Serverless front-end is to upload static files such as HTML, CSS, and JS to CDN or object storage services. Common options are:

• AWS S3 CloudFront
• Vercel / Netlify (simpler, suitable for front-end developers)
• Cloudflare Pages

Most of these platforms support automatic construction and deployment processes. You only need to configure the Git repository and automatically go online every time you push it.

Note that although CDN is fast, sometimes you need to manually set the cache policy. For example, HTML files should not be cached for too long. JS/CSS can be cached for a longer time to avoid the user not loading the new version after update.

2. The backend function is implemented using cloud functions

If your front-end needs to access the database, send emails, process images and other tasks, you can use "cloud functions" to complete it. for example:

• Form Submission → Trigger a Lambda function to save data or send emails
• Login verification → Use serverless authentication solutions such as Auth0 or Supabase
• Image Cropping → Call the image processing library with cloud functions and return the results

The writing methods of different platforms vary slightly, but the overall structure is similar: HTTP requests are received → Processing logic → Return JSON data.

To give a simple example, a function that obtains user information may look like this on Vercel:

 export default function handler(req, res) {
  const user = getUserFromDB(req.query.id);
  res.json(user);
}

This type of function is usually free enough for small items to use, and then billed according to the number of requests after the amount exceeds the amount.

3. How to deal with the database?

Since there is no server, where does the data exist? Now there are many Serverless databases or low-code solutions to choose from:

• Supabase : Open source replaces Firebase, with its own functions such as authentication and real-time updates
• AWS DynamoDB : NoSQL, easy to use with Lambda
• PlanetScale / Neon (Serverless version of PostgreSQL) : Suitable for scenarios where SQL is needed
• Airtable / Notion API : Suitable for quick construction of small projects or MVPs

These databases generally provide REST API or SDK, which can be called directly from cloud functions without having to build an intermediate layer by yourself.

4. Small details on safety and performance

Although Serverless is convenient, there are some things that are easy to overlook:

• Be careful with permission control : For example, don’t let cloud functions expose too much data, it is recommended to add a layer of authentication
• API key management : Don't write it directly in front-end code, you can use environment variable cloud functions to transfer it.
• Cold startup problem : Some cloud function platforms will be slower for the first time. If the performance requirements are high, you can consider retaining instances (such as AWS Provisioned Concurrency)

In addition, after the front and back ends are separated, cross-domain issues must also be handled well. For example, if your front-end is deployed in example.com and the cloud function is in api.example.com , then CORS must be configured.

Basically that's it. Serverless is a front-end application, not complicated but it is easy to ignore details. As long as existing tools are used reasonably, development efficiency and operation and maintenance costs can be reduced.

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