CORS (Cross-Origin Resource Sharing)

To invoke edge functions from the browser, you need to handle CORS Preflight requests.

See the example on GitHub.

Recommended setup#

We recommend adding a cors.ts file within a _shared folder which makes it easy to reuse the CORS headers across functions:

export const corsHeaders = {
  'Access-Control-Allow-Origin': '*',
  'Access-Control-Allow-Headers': 'authorization, x-client-info, apikey, content-type',
}

You can then import and use the CORS headers within your functions:

import { serve } from 'https://deno.land/std@0.177.0/http/server.ts'
import { corsHeaders } from '../_shared/cors.ts'

console.log(`Function "browser-with-cors" up and running!`)

serve(async (req) => {
  // This is needed if you're planning to invoke your function from a browser.
  if (req.method === 'OPTIONS') {
    return new Response('ok', { headers: corsHeaders })
  }

  try {
    const { name } = await req.json()
    const data = {
      message: `Hello ${name}!`,
    }

    return new Response(JSON.stringify(data), {
      headers: { ...corsHeaders, 'Content-Type': 'application/json' },
      status: 200,
    })
  } catch (error) {
    return new Response(JSON.stringify({ error: error.message }), {
      headers: { ...corsHeaders, 'Content-Type': 'application/json' },
      status: 400,
    })
  }
})