JavaScript Examples ⁠-⁠ Adding a response header

Based on the country code, accessed through event.request.metadata["geoip_country_code"], a response header is added by event.addResponseHeader().

async function firewallHandler(event){
// Access the country code through geoip
let countryCode = event.request.metadata["geoip_country_code"]
// Do some logic here
// In this example, if the request comes from Brazil, we add a header to the response
if (countryCode === "BR"){
event.addResponseHeader("test", "true");
// Then, if it comes from any other country,
// the processing continues
addEventListener("firewall", (event)=>event.waitUntil(firewallHandler(event)));