Workers - Handle incoming request cancellation in Workers with Request.signal

In Cloudflare Workers, you can now attach an event listener to Request objects, using the signal property . This allows you to perform tasks when the request to your Worker is canceled by the client. To use this feature, you must set the enable_request_signal compatibility flag. You can use a listener to perform cleanup tasks or write to logs before your Worker's invocation ends. For example, if you run the Worker below, and then abort the request from the client, a log will be written: JavaScript export default { async fetch ( request , env , ctx ) { // This sets up an event listener that will be called if the client disconnects from your // worker. request . signal . addEventListener ( "abort" , () => { console . log ( "The request was aborted!" ) ; } ) ; const { readable , writable } = new IdentityTransformStream () ; sendPing ( writable ) ; return new Response ( readable , { headers : { "Content-Type" : "text/plain" }, } ) ; }, }; async function sendPing ( writable ) { const writer = writable . getWriter () ; const enc = new TextEncoder () ; for ( ;; ) { // Send 'ping' every second to keep the connection alive await writer . write ( enc . encode ( "ping \r\n " )) ; await scheduler . wait ( 1000 ) ; } } TypeScript export default { async fetch ( request , env , ctx ) : Promise < Response > { // This sets up an event listener that will be called if the client disconnects from your // worker. request . signal . addEventListener ( 'abort' , () => { console . log ( 'The request was aborted!' ) ; } ) ; const { readable , writable } = new IdentityTransformStream () ; sendPing ( writable ) ; return new Response ( readable , { headers : { 'Content-Type' : 'text/plain' } } ) ; }, } satisfies ExportedHandler < Env >; async function sendPing ( writable : WritableStream ) : Promise < void > { const writer = writable . getWriter () ; const enc = new TextEncoder () ; for ( ;; ) { // Send 'ping' every second to keep the connection alive await writer . write ( enc . encode ( 'ping \r\n ' )) ; await scheduler . wait ( 1000 ) ; } } For more information see the Request documentation .