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<!doctype html>
<meta charset="utf-8">
<script>
const dbName = "users";
// Create the database at v1 and detect success via `onsuccess`.
function createDatabase() {
return new Promise((resolve, reject) => {
var dbRequest = window.indexedDB.open(dbName, 1);
dbRequest.onblocked = () => reject();
dbRequest.onerror = () => reject();
dbRequest.onsuccess = (e) => {
e.target.result.close();
resolve();
}
});
}
// Open the database at v2 and detect existance via `onupgradeneeded`.
function doesDatabaseExist() {
let didExist = false;
return new Promise((resolve, reject) => {
var dbRequest = window.indexedDB.open(dbName, 2);
dbRequest.onblocked = () => reject();
dbRequest.onerror = () => reject();
dbRequest.onsuccess = (e) => {
e.target.result.close();
deleteDatabase().then(() => resolve(didExist));
};
dbRequest.onupgradeneeded = (e) => {
didExist = e.oldVersion != 0;
};
});
}
// Delete the database and detect success via `onsuccess`.
function deleteDatabase() {
return new Promise((resolve, reject) => {
var dbRequest = window.indexedDB.deleteDatabase(dbName);
dbRequest.onblocked = () => reject();
dbRequest.onerror = () => reject();
dbRequest.onsuccess = () => resolve();
});
}
// Step 2
window.addEventListener("load", () => {
parent.postMessage(
{message: "iframe loaded"},
"*",
);
});
window.addEventListener("message", (e) => {
if (e.data.message == "create database") {
// Step 4
createDatabase().then(() => {
parent.postMessage(
{message: "database created"},
"*",
);
});
} else if (e.data.message == "check database") {
// Step 6
doesDatabaseExist().then((result) => {
parent.postMessage(
{
message: "database checked",
doesDatabaseExist: result,
},
"*",
);
});
}
});
</script>