Promise.catch()

Syntax

promise.catch(function (error) {
    ...
});

Return Value

The method will return another Promise that will resolve with the return value of given callback.

Remarks

Supplying a callback to run if the promise fails. The return value of the catch callback will work as the resolve value for the returned promise.

Samples

Catching Error Events

var db = new Dexie('db');
db.version(1).stores({friends: 'email,name'});
db.open();

// Un-remark following line to make it fail due to ConstraintError:
//  db.friends.add({email: "abc@def.com", name: "Oliver"}); 
db.friends.add({email: "abc@def.com", name: "Gertrud"}).then(function() {
    alert ("Successfully added friend into DB");
}).catch (function (e) {
    alert ("Failed to add friend into DB: " + e);
});

Catching Thrown Exceptions

var db = new Dexie('db');
db.version(1).stores({friends: 'email,name'});
db.open();

db.friends.add({email: "abc@def.com", name: "Gertrud"}).then(function() {
    throw new Error ("Ha ha ha!");
}).catch (function (e) {
    alert ("Failed: " + e.toString());
});

Catching Specific Error Types

var db = new Dexie('db');
db.version(1).stores({friends: 'email,name'});
db.open();

// Un-remark following line to make it fail due to ConstraintError:
//  db.friends.add({email: "abc@def.com", name: "Oliver"}); 
db.friends.add({email: "abc@def.com", name: "Gertrud"}).then(function() {
    alert ("Successfully added friend into DB");
}).catch (DOMError, function (e) {
    alert ("DOMError occurred: " + e);
}).catch (function (e) {
    alert ("Unknown error occurred: " + e);
});

Catching Error of Specific 'name'

Sometimes the error type doesnt tell exactly what error occurred. IndexedDB for example, will always fail with a DOMError, where its name property tells the actual reason. Dexie.Promise has support for supplying a string as first argument. By doing that, the name property of the error is cheched against the given string.

var db = new Dexie('db');
db.version(1).stores({friends: 'email,name'});
db.open();

// Un-remark following line to make it fail due to ConstraintError:
//  db.friends.add({email: "abc@def.com", name: "Oliver"}); 
db.friends.add({email: "abc@def.com", name: "Gertrud"}).then(function() {
    alert ("Successfully added friend into DB");
}).catch ('ConstraintError', function (e) {
    alert ("ConstraintError occurred: " + e);
}).catch (function (e) {
    alert ("Unknown error occurred: " + e);
});

See Also