CORS issues in Vue occur due to the browser's same-origin policy when the frontend and backend domains differ. During development, configure a proxy in vue.config.js to redirect API requests through the dev server. In production, ensure the backend sets proper CORS headers, allowing specific origins instead of using wildcards for security. Some deployment platforms also support edge functions to avoid CORS by hosting APIs on the same domain. Use environment variables for API URLs and test backend endpoints independently with tools like Postman.

CORS (Cross-Origin Resource Sharing) is a mechanism that allows or restricts web applications from making requests to a different domain than the one serving the application. This is important in Vue development because most Vue apps are front-end clients that communicate with APIs, which may be hosted on a different domain.

What causes CORS issues in Vue?

When developing a Vue app using tools like Vue CLI or Vite, you often run the development server on localhost:8080 or similar, while your API might be running on localhost:3000 or another domain altogether. Browsers enforce same-origin policy for security reasons, meaning if the domain, port, or protocol differs between the frontend and backend, the browser will block the request unless the server explicitly allows it.

This shows up as an error in the browser console like:

Blocked by CORS policy: No 'Access-Control-Allow-Origin' header present.

It’s not a bug in your Vue code — it’s a browser-enforced security measure.

How do you handle CORS during development?

During development, you can work around CORS restrictions using a proxy configured in your Vue project. In Vue CLI, this is done via the vue.config.js file. Here's how:

// vue.config.js
module.exports = {
  devServer: {
    proxy: {
      '/api': {
        target: 'http://localhost:3000',
        changeOrigin: true,
        pathRewrite: { '^/api': '' }
      }
    }
  }
}

With this setup:

• Any request made to /api in your Vue app will be redirected to http://localhost:3000.
• The browser sees the request as coming from the same origin since it's hitting the dev server first.
• This only works during development — it doesn’t affect production builds.

This is a common and effective workaround when your backend isn't set up to allow cross-origin requests yet.

What about handling CORS in production?

In production, the proxy approach won’t work anymore. At this point, you need the backend to properly configure CORS headers. For example, a Node.js Express server could allow cross-origin requests like this:

app.use((req, res, next) => {
  res.header('Access-Control-Allow-Origin', '*');
  res.header('Access-Control-Allow-Headers', 'Origin, X-Requested-With, Content-Type, Accept');
  next();
});

But allowing all origins (*) might not be secure for real applications. You’d want to specify exact allowed domains instead.

If you're deploying your Vue app to a service like Netlify or Vercel, you don’t have direct control over server headers. So again, the backend must support CORS correctly.

Also, some cloud providers offer edge functions or serverless functions that let you create an API endpoint on the same domain as your Vue app, effectively avoiding CORS issues.

A few small tips

• Use environment variables to manage API URLs so switching between dev and prod is easier.
• Tools like Postman or curl aren’t affected by CORS — useful for testing backend responses directly.
• Preflight requests (OPTIONS) are part of CORS. If your API doesn’t respond properly to them, the browser blocks the actual request before it even happens.

Basically, dealing with CORS in Vue is less about Vue itself and more about how the backend is set up and how you configure your development environment.

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