[PWA] 16. Clean IDB
时间：2021-07-01 10:21:17
帮助过：2人阅读
var messages =
JSON.parse(data);
this._dbPromise.then(function(db) {
if (!db)
return;
var tx = db.transaction(
‘wittrs‘,
‘readwrite‘);
var store = tx.objectStore(
‘wittrs‘);
messages.forEach(function(message) {
store.put(message);
});
// TODO: keep the newest 30 entries in ‘wittrs‘,
// but delete the rest.
//
// Hint: you can use .openCursor(null, ‘prev‘) to
// open a cursor that goes through an index/store
// backwards.
store.index(
‘by-date‘).openCursor(
null,
‘prev‘)
.then((cursor)=>
{
return cursor.advance(
30);
// only 30 itmes are kept
}).then(function deleteCursor(cursor){
if(!
cursor){
return;
}else{
cursor.delete();
return cursor.
continue().then(deleteCursor);
}
})
});
this._postsView.addPosts(messages);
};
[PWA] 16. Clean IDB
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