IDBDatabase: versionchange 事件
當在其他地方（很可能是在同一臺計算機上的另一個視窗/標籤頁中）請求更改資料庫結構（在 IDBOpenDBRequest 上傳送 upgradeneeded 事件或呼叫 IDBFactory.deleteDatabase）時，會觸發 versionchange 事件。
語法
在諸如 addEventListener() 之類的方法中使用事件名稱，或設定事件處理程式屬性。
js
addEventListener("versionchange", (event) => { })
onversionchange = (event) => { }
事件型別
一個通用的 Event。
示例
此示例開啟一個數據庫，成功後新增一個 versionchange 監聽器
js
// Open the database
const dBOpenRequest = window.indexedDB.open("Nonexistent", 4);
dBOpenRequest.onupgradeneeded = (event) => {
const db = event.target.result;
// Create an objectStore for this database
const objectStore = db.createObjectStore("toDoList", {
keyPath: "taskTitle",
});
// define what data items the objectStore will contain
objectStore.createIndex("hours", "hours", { unique: false });
objectStore.createIndex("minutes", "minutes", { unique: false });
objectStore.createIndex("day", "day", { unique: false });
objectStore.createIndex("month", "month", { unique: false });
objectStore.createIndex("year", "year", { unique: false });
};
dBOpenRequest.addEventListener("success", (event) => {
const db = event.target.result;
db.addEventListener("versionchange", (event) => {
console.log("The version of this database has changed");
});
});
同一示例，使用 onversionchange 事件處理程式屬性
js
// Open the database
const dBOpenRequest = window.indexedDB.open("Nonexistent", 4);
dBOpenRequest.onupgradeneeded = (event) => {
const db = event.target.result;
// Create an objectStore for this database
const objectStore = db.createObjectStore("toDoList", {
keyPath: "taskTitle",
});
// define what data items the objectStore will contain
objectStore.createIndex("hours", "hours", { unique: false });
objectStore.createIndex("minutes", "minutes", { unique: false });
objectStore.createIndex("day", "day", { unique: false });
objectStore.createIndex("month", "month", { unique: false });
objectStore.createIndex("year", "year", { unique: false });
};
dBOpenRequest.onsuccess = (event) => {
const db = event.target.result;
db.onversionchange = (event) => {
console.log("The version of this database has changed");
};
};
規範
| 規範 |
|---|
| Indexed Database API 3.0 # eventdef-idbdatabase-versionchange |
| Indexed Database API 3.0 # dom-idbdatabase-onversionchange |
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