IDBDatabase: versionchange 事件

当数据库结构发生更改时，会触发 versionchange 事件 (upgradeneeded 事件发送到 IDBOpenDBRequest 或 IDBFactory.deleteDatabase) 被请求到其他地方（很可能是在同一台计算机上的另一个窗口/选项卡中）。

语法

在像 addEventListener() 这样的方法中使用事件名称，或者设置事件处理程序属性。

addEventListener("versionchange", (event) => {});
onversionchange = (event) => {};

事件类型

一个通用的 Event。

示例

此示例打开一个数据库，并在成功后添加一个监听器到 versionchange

// 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");
  });
});

使用 onversionchange 事件处理程序属性的相同示例

// 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");
  };
};

浏览器兼容性

BCD 表格只在浏览器中加载

另请参阅

使用 IndexedDB