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hydrogen-web/prototypes/idb-promises.html
2020-09-25 11:19:59 +02:00

181 lines
6.3 KiB
HTML

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
</head>
<body>
<!-- <script type="text/javascript" src="promifill.js"></script> -->
<script type="text/javascript">
const PENDING = 1;
const RESOLVED = 2;
const REJECTED = 3;
function noop() {};
function SyncPromise(fn) {
this._listeners = [];
this._value = null;
this._state = PENDING;
fn(this._resolve.bind(this), this._reject.bind(this));
}
SyncPromise.prototype = {
then: function(onResolved, onRejected) {
if (this._state === PENDING) {
this._listeners.push({onRejected: onRejected, onResolved: onResolved});
} else if (this._state === RESOLVED) {
onResolved(this._value);
} else if (this._state === REJECTED) {
onRejected(this._value);
}
return this;
},
catch: function(onRejected) {
return this.then(noop, onRejected);
},
finally: function(onResolved) {
return this.then(onResolved, noop);
},
_chain: function(value) {
if (value && typeof value.then === "function") {
value.then(function(value) {
self._resolve(value);
}, function(err) {
self._reject(err);
});
return true;
} else {
return false;
}
},
_resolve: function(value) {
if (!this._chain(value)) {
this._state = RESOLVED;
this._value = value;
for (var i = 0; i < this._listeners.length; i += 1) {
this._listeners[i].onResolved(value);
}
}
},
_reject: function(err) {
this._state = REJECTED;
this._value = err;
for (var i = 0; i < this._listeners.length; i += 1) {
this._listeners[i].onRejected(err);
}
}
}
SyncPromise.resolve = function(value) {
return new SyncPromise(function(resolve) {
resolve(value);
});
}
SyncPromise.reject = function(value) {
return new SyncPromise(function(_, reject) {
reject(value);
});
}
window.Promise = SyncPromise;
</script>
<!-- <script src="https://cdn.jsdelivr.net/npm/promise-polyfill@8/dist/polyfill.min.js"></script> -->
<script type="text/javascript">
function reqAsPromise(req) {
return new Promise(function (resolve, reject) {
req.onsuccess = function() {resolve(req);};
req.onerror = function(e) {reject(new Error("IDB request failed: " + e.target.error.message));};
});
}
function Storage(databaseName) {
this._databaseName = databaseName;
this._database = null;
}
Storage.prototype = {
open: function() {
const req = window.indexedDB.open(this._databaseName);
const self = this;
req.onupgradeneeded = function(ev) {
const db = ev.target.result;
const oldVersion = ev.oldVersion;
self._createStores(db, oldVersion);
};
return reqAsPromise(req).then(function() {
self._database = req.result;
});
},
openTxn: function(mode, storeName) {
const tx = this._database.transaction([storeName], mode);
const store = tx.objectStore(storeName);
return Promise.resolve(store);
},
_createStores: function(db) {
db.createObjectStore("foos", {keyPath: ["id"]});
}
};
function getAll(store) {
const request = store.openCursor();
const results = [];
return new Promise(function(resolve, reject) {
request.onsuccess = function(event) {
const cursor = event.target.result;
if(cursor) {
results.push(cursor.value);
cursor.continue();
} else {
resolve(results);
}
};
request.onerror = function(e) {reject(new Error("IDB request failed: " + e.target.error.message));};
});
}
function main() {
let storage = new Storage("idb-promises");
let store;
storage.open().then(function() {
return storage.openTxn("readwrite", "foos");
}).then(function(s) {
store = s;
store.clear();
store.add({id: 5, name: "foo"});
store.add({id: 6, name: "bar"});
return getAll(store);
}).then(function(all) {
console.log("all1", all);
store.add({id: 7, name: "bazzz"});
return getAll(store);
}).then(function(all) {
console.log("all2", all);
}).catch(function(err) {
console.error(err.message + ": " + err.stack);
});
}
main();
/*
we basically want something like this for IE11/Win7:
return new Promise(function (resolve, reject) {
req.onsuccess = function() {
resolve(req);
Promise?.flushQueue();
};
req.onerror = function(e) {
reject(new Error("IDB request failed: " + e.target.error.message));
Promise?.flushQueue();
};
});
we don't have this problem on platforms with a native promise implementation, so we can just have our own (forked) promise polyfill?
*/
</script>
</body>
</html>