html5本地数据库查询

// 打开数据库
let request = indexedDB.open("myDatabase", 1);

request.onupgradeneeded = function(event) {
  let db = event.target.result;
  let objectStore = db.createObjectStore("users", { keyPath: "id" });
  objectStore.createIndex("name", "name", { unique: false });
};

request.onsuccess = function(event) {
  let db = event.target.result;
  let transaction = db.transaction(["users"], "readonly");
  let objectStore = transaction.objectStore("users");
  let index = objectStore.index("name");

  // 查询名字为"John"的用户
  let request = index.openCursor(IDBKeyRange.only("John"));

  request.onsuccess = function(event) {
    let cursor = event.target.result;
    if (cursor) {
      console.log("User:", cursor.value);
      cursor.continue();
    }
  };
};

request.onerror = function(event) {
  console.error("Database error: ", event.target.errorCode);
};