IDBCursor | Web API

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注意： Not to be confused with IDBCursorWithValue which is just an IDBCursor interface with an additional value 特性。

IDBCursor 接口在 IndexedDB API represents a cursor for traversing or iterating over multiple records in a database.

The cursor has a source that indicates which index or object store it is iterating over. It has a position within the range, and moves in a direction that is increasing or decreasing in the order of record keys. The cursor enables an application to asynchronously process all the records in the cursor's range.

You can have an unlimited number of cursors at the same time. You always get the same IDBCursor object representing a given cursor. Operations are performed on the underlying index or object store.

注意： 此特征可用于 Web 工作者 .

特性

注意： IDBCursorWithValue 是 IDBCursor interface with an additional value 特性。

IDBCursor.source 只读: 返回 IDBObjectStore or IDBIndex that the cursor is iterating. This function never returns null or throws an exception, even if the cursor is currently being iterated, has iterated past its end, or its transaction is not active.
IDBCursor.direction 只读: Returns the direction of traversal of the cursor. See 常量对于可能的值。
IDBCursor.key 只读: Returns the key for the record at the cursor's position. If the cursor is outside its range, this is set to undefined . The cursor's key can be any data type.
IDBCursor.primaryKey 只读: Returns the cursor's current effective primary key. If the cursor is currently being iterated or has iterated outside its range, this is set to undefined . The cursor's primary key can be any data type.
IDBCursor.request 只读: 返回 IDBRequest that was used to obtain the cursor.

方法

IDBCursor.advance()
IDBCursor.continue(): Advances the cursor to the next position along its direction, to the item whose key matches the optional key 参数。
IDBCursor.continuePrimaryKey()

IDBCursor.delete(): 返回 IDBRequest object, and, in a separate thread, deletes the record at the cursor's position, without changing the cursor's position. This can be used to delete specific records.
IDBCursor.update(): 返回 IDBRequest object, and, in a separate thread, updates the value at the current position of the cursor in the object store. This can be used to update specific records.

常量

Deprecated since Gecko 13 (Firefox 13 / Thunderbird 13 / SeaMonkey 2.10)
This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the 兼容性表格 at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

These constants are no longer available — they were removed in Gecko 25. You should use the string constants directly instead. ( bug 891944 )

NEXT : "next" : The cursor shows all records, including duplicates. It starts at the lower bound of the key range and moves upwards (monotonically increasing in the order of keys).
NEXTUNIQUE : "nextunique" : The cursor shows all records, excluding duplicates. If multiple records exist with the same key, only the first one iterated is retrieved. It starts at the lower bound of the key range and moves upwards.
PREV : "prev" : The cursor shows all records, including duplicates. It starts at the upper bound of the key range and moves downwards (monotonically decreasing in the order of keys).
PREVUNIQUE : "prevunique" : The cursor shows all records, excluding duplicates. If multiple records exist with the same key, only the first one iterated is retrieved. It starts at the upper bound of the key range and moves downwards.

范例

In this simple fragment we create a transaction, retrieve an object store, then use a cursor to iterate through all the records in the object store. The cursor does not require us to select the data based on a key; we can just grab all of it. Also note that in each iteration of the loop, you can grab data from the current record under the cursor object using cursor.value.foo . For a complete working example, see our IDBCursor example ( 实时查看范例 )。

function displayData() {
  var transaction = db.transaction(['rushAlbumList'], "readonly");
  var objectStore = transaction.objectStore('rushAlbumList');
  objectStore.openCursor().onsuccess = function(event) {
    var cursor = event.target.result;
    if(cursor) {
      var listItem = document.createElement('li');
      listItem.innerHTML = cursor.value.albumTitle + ', ' + cursor.value.year;
      list.appendChild(listItem);
      cursor.continue();
    } else {
      console.log('Entries all displayed.');
    }
  };
}

规范

规范	状态	注释
索引数据库 API 2.0 The definition of 'cursor' in that specification.	推荐	初始定义
索引数据库 API 草案 The definition of 'cursor' in that specification.	推荐	添加 `continuePrimaryKey()` and support for binary keys, and the `IDBCursor.request` 特性。

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`IDBCursor`	Chrome 24 24 23 — 57 Prefixed Prefixed Implemented with the vendor prefix: webkit	Edge 12	Firefox 16 16 10 — 16 Prefixed Prefixed Implemented with the vendor prefix: moz	IE 部分支持 10	Opera 44 44 15 — 44 Prefixed Prefixed Implemented with the vendor prefix: webkit	Safari 7	WebView Android Yes Yes ? — 57 Prefixed Prefixed Implemented with the vendor prefix: webkit	Chrome Android 25 25 25 — 57 Prefixed Prefixed Implemented with the vendor prefix: webkit	Firefox Android 22	Opera Android 43 43 14 — 43 Prefixed Prefixed Implemented with the vendor prefix: webkit	Safari iOS 8	Samsung Internet Android 1.5 1.5 1.5 — 7.0 Prefixed Prefixed Implemented with the vendor prefix: webkit
`advance`	Chrome 24 24 23 — 24 Prefixed Prefixed Implemented with the vendor prefix: webkit	Edge 12	Firefox 16 16 10 — 16 Prefixed Prefixed Implemented with the vendor prefix: moz	IE 部分支持 10	Opera 15	Safari 7	WebView Android Yes	Chrome Android Yes	Firefox Android 22	Opera Android 14	Safari iOS 8	Samsung Internet Android Yes
`continue`	Chrome 24 24 23 — 24 Prefixed Prefixed Implemented with the vendor prefix: webkit	Edge 12	Firefox 16 16 10 — 16 Prefixed Prefixed Implemented with the vendor prefix: moz	IE 部分支持 10	Opera 15	Safari 7	WebView Android Yes	Chrome Android Yes	Firefox Android 22	Opera Android 14	Safari iOS 8	Samsung Internet Android Yes
`continuePrimaryKey`	Chrome 58	Edge 79	Firefox 51 51 10 — 51 Prefixed Prefixed Implemented with the vendor prefix: moz	IE ?	Opera 45	Safari 10.1	WebView Android 58	Chrome Android 58	Firefox Android 51	Opera Android 43	Safari iOS 10.3	Samsung Internet Android 7.0
`delete`	Chrome 24 24 23 — 24 Prefixed Prefixed Implemented with the vendor prefix: webkit	Edge 12	Firefox 16 16 10 — 16 Prefixed Prefixed Implemented with the vendor prefix: moz	IE 部分支持 10	Opera 15	Safari 7	WebView Android Yes	Chrome Android Yes	Firefox Android 22	Opera Android 14	Safari iOS 8	Samsung Internet Android Yes
`direction`	Chrome 24 24 23 — 24 Prefixed Prefixed Implemented with the vendor prefix: webkit	Edge 12	Firefox 16 16 10 — 16 Prefixed Prefixed Implemented with the vendor prefix: moz	IE 部分支持 10	Opera 15	Safari 7	WebView Android Yes	Chrome Android Yes	Firefox Android 22	Opera Android 14	Safari iOS 8	Samsung Internet Android Yes
`key`	Chrome 24 24 23 — 24 Prefixed Prefixed Implemented with the vendor prefix: webkit	Edge 12	Firefox 16 16 10 — 16 Prefixed Prefixed Implemented with the vendor prefix: moz	IE 部分支持 10	Opera 15	Safari 7	WebView Android Yes	Chrome Android Yes	Firefox Android 22	Opera Android 14	Safari iOS 8	Samsung Internet Android Yes
`primaryKey`	Chrome 24 24 23 — 24 Prefixed Prefixed Implemented with the vendor prefix: webkit	Edge 12	Firefox 16 16 10 — 16 Prefixed Prefixed Implemented with the vendor prefix: moz	IE 部分支持 10	Opera 15	Safari 7	WebView Android Yes	Chrome Android Yes	Firefox Android 22	Opera Android 14	Safari iOS 8	Samsung Internet Android Yes
`request`	Chrome 76	Edge 79	Firefox 77	IE 不支持 No	Opera 63	Safari ?	WebView Android 76	Chrome Android 76	Firefox Android 不支持 No	Opera Android 54	Safari iOS ?	Samsung Internet Android 12.0
`source`	Chrome 24 24 23 — 24 Prefixed Prefixed Implemented with the vendor prefix: webkit	Edge 12	Firefox 16 16 10 — 16 Prefixed Prefixed Implemented with the vendor prefix: moz	IE 部分支持 10	Opera 15	Safari 7	WebView Android Yes	Chrome Android Yes	Firefox Android 22	Opera Android 14	Safari iOS 8	Samsung Internet Android Yes
`update`	Chrome 24 24 23 — 24 Prefixed Prefixed Implemented with the vendor prefix: webkit	Edge 12	Firefox 16 16 10 — 16 Prefixed Prefixed Implemented with the vendor prefix: moz	IE 部分支持 10	Opera 15	Safari 7	WebView Android Yes	Chrome Android Yes	Firefox Android 22	Opera Android 14	Safari iOS 8	Samsung Internet Android Yes
Available in workers	Chrome 24 24 23 — 57 Prefixed Prefixed Implemented with the vendor prefix: webkit	Edge ≤18	Firefox 37	IE ?	Opera 44 44 15 — 44 Prefixed Prefixed Implemented with the vendor prefix: webkit	Safari 7	WebView Android Yes Yes ? — 57 Prefixed Prefixed Implemented with the vendor prefix: webkit	Chrome Android 25 25 25 — 57 Prefixed Prefixed Implemented with the vendor prefix: webkit	Firefox Android 37	Opera Android Yes Yes 14 — 43 Prefixed Prefixed Implemented with the vendor prefix: webkit	Safari iOS ?	Samsung Internet Android 1.5 1.5 1.5 — 7.0 Prefixed Prefixed Implemented with the vendor prefix: webkit

图例

完整支持
部分支持
不支持
兼容性未知 ?
要求使用供应商前缀或不同名称。

另请参阅

使用 IndexedDB
开始事务： IDBDatabase
使用事务： IDBTransaction
设置一系列键： IDBKeyRange
检索并使您的数据改变： IDBObjectStore
使用光标： IDBCursor
参考范例：待办通知 ( 实时查看范例 )。

元数据

最后修改： May 18, 2020

IndexedDB API
IDBCursor
特性
1. direction
2. key
3. primaryKey
4. request
5. source
方法
IndexedDB 相关页面

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方法

常量

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规范

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另请参阅

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