Abort asynchronous task

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How to abort Asynchronous task


There’s a special built-in object for such purposes: AbortController . It can be used to abort not only fetch , but other asynchronous tasks as well.
The usage is very straightforward:

The AbortController object


Create a controller:
let controller = new AbortController();
A controller is an extremely simple object.
  • It has a single method abort() ,
  • And a single property signal that allows to set event listeners on it.
    • When abort() is called:
  • controller.signal emits the "abort" event.
  • controller.signal.aborted property becomes true .
    • Generally, we have two parties in the process:
  • The one that performs a cancelable operation, it sets a listener on controller.signal .
  • The one that cancels: it calls controller.abort() when needed.
    • When a fetch is aborted, its promise rejects with an error AbortError , so we should handle it, e.g. in try..catch .
    約束通りにFetch方法を管理する.
    let controller = new AbortController();
let signal = controller.signal;

// The party that performs a cancelable operation
// gets the "signal" object
// and sets the listener to trigger when controller.abort() is called
signal.addEventListener('abort', () => alert("abort!"));

// The other party, that cancels (at any point later):
controller.abort(); // abort!

// The event triggers and signal.aborted becomes true
alert(signal.aborted); // true
    with the fetch()
    // abort in 1 second
let controller = new AbortController();
setTimeout(() => controller.abort(), 1000);

try {
  let response = await fetch('/article/fetch-abort/demo/hang', {
    signal: controller.signal
  });
} catch(err) {
  if (err.name == 'AbortError') { // handle abort()
    alert("Aborted!");
  } else {
    throw err;
  }
}
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