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const STORAGE_NAME = 'prerender_test';
const INITIATOR_KEY = 'initiator';
const INITIATOR_VALUE = INITIATOR_KEY + '_set';
const PRERENDER_KEY = 'prerender';
const PRERENDER_VALUE = PRERENDER_KEY + '_set';
async function openIndexedDatabase(t) {
return new Promise(resolve => {
const request = window.indexedDB.open(STORAGE_NAME);
if (t)
t.add_cleanup(() => new Promise(resolve => {
window.indexedDB.deleteDatabase(STORAGE_NAME);
resolve();
}));
request.onupgradeneeded = e => {
const db = e.target.result;
const objectStore =
db.createObjectStore(STORAGE_NAME, {autoIncrement: true});
objectStore.createIndex('key', 'key', {unique: true});
};
request.onerror = e => {
resolve(null);
};
request.onsuccess = e => {
resolve(e.target.result);
};
});
}
async function addData(db, key, value) {
return new Promise((resolve, reject) => {
const transaction = db.transaction(STORAGE_NAME, 'readwrite');
const request =
transaction.objectStore(STORAGE_NAME).add({'key': key, 'value': value});
// Use `transaction.oncomplete` rather than `request.onsuccess` to ensure
// that IndexedDB has flushed to disk.
transaction.oncomplete = e => {
resolve(true);
};
transaction.onerror = e => {
reject(e.target.error);
};
});
}
async function readData(db, key) {
return new Promise((resolve, reject) => {
const transaction = db.transaction(STORAGE_NAME);
const request = transaction.objectStore(STORAGE_NAME).index('key').get(key);
request.onsuccess = e => {
if (e.target.result) {
resolve(e.target.result.value);
} else {
reject(new Error('Empty result.'));
}
};
request.onerror = e => {
reject(e.target.error);
};
});
}