Promise.prototype.catch()

Method catch() mengembalikan Promise dan hanya setuju jika kasusnya gagal. Sama halnya dengan memenggil method Promise.prototype.then(undefined, onRejected).

Sintaks

p.catch(onRejected);

p.catch(function(reason) {
   // rejection
});

Parameter

onRejected

 Function dipanggil ketika Promise ditolak. Fungsi ini memiliki satu argumen, alasan penolakan.

Deskripsi

Method catch sangat berguna untuk menangani error di gabungan promis anda.

Contoh

Penggunaan method catch

var p1 = new Promise(function(resolve, reject) {
  resolve('Success');
});

p1.then(function(value) {
  console.log(value); // "Success!"
  throw 'oh, no!';
}).catch(function(e) {
  console.log(e); // "oh, no!"
}).then(function(){
  console.log('after a catch the chain is restored');
}, function () {
  console.log('Not fired due to the catch');
});

// The following behaves the same as above
p1.then(function(value) {
  console.log(value); // "Success!"
  return Promise.reject('oh, no!');
}).catch(function(e) {
  console.log(e); // "oh, no!"
}).then(function(){
  console.log('after a catch the chain is restored');
}, function () {
  console.log('Not fired due to the catch');
});

Promis tidak dapat mendeteksi error pada asynchronous callback

var p1 = new Promise(function(resolve, reject) {
  throw 'Uh-oh!';
});

p1.catch(function(e) {
  console.log(e); // "Uh-oh!"
});


var p2 = new Promise(function(resolve, reject) {
  setTimeout(function() {
    throw 'Uncaught Exception!';
  }, 1000);
});

p2.catch(function(e) {
  console.log(e); // This is never called
});

Spesifikasi

Kompabilitas Browser

Lihat Juga

• Promise
• Promise.prototype.then()