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Promise.onuncatched

David Fahlander edited this page Apr 3, 2014 · 4 revisions

Called if the promise wasnt catched.

Sample

var p = new Promise(function (resolve, reject) {
    reject("Failed!");
});
p.onuncatched = function (e) {
    alert ("No-one catched this error: " + e);
}

Result:

Since neither then(x, f), catch(f) or finally(f) was called with valid function f, the alert would be fired.

How this is used in Dexie

Dexie uses this event on all returned promises from any DB operation on a Transaction in order to make sure error is propagated to the transaction and that transaction is aborted.

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