blob: 573890a7fad01e54758f6e073cd5be8eaca87435 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
|
---
title: IDBCursor.key
slug: Web/API/IDBCursor/key
translation_of: Web/API/IDBCursor/key
---
<p>{{APIRef("IndexedDB")}}</p>
<div>
<p><strong>key</strong>是只读属性，返回在游标中的位置。如果游标在范围之外，这个值会被置为undefined。游标的key可以是任何数据类型。</p>
<p>{{AvailableInWorkers}}</p>
</div>
<h2 id="语法">语法</h2>
<pre class="syntaxbox" style="font-size: 14px;">var <em>key = cursor</em>.key;</pre>
<h3 id="值">值</h3>
<p>任意类型</p>
<h2 id="示例">示例</h2>
<p>在该示例中，我们创建一个事务，检索一个存储对象，然后使用游标遍历所有存储在object store 中的记录。遍历的过程中，我们把类似（相簿标题，这是我们的键key），游标的key打印出来。</p>
<p>我们可以不根据游标的key来选取数据；我们可以抓取所有。还要注意，在循环的每个迭代中，您可以使用cursor.value.foo从当前记录下获取数据。完整示例，请看<span style="line-height: 1.5;"><a href="https://github.com/mdn/IDBcursor-example/">IDBCursor example</a></span><span style="line-height: 1.5;"> (</span><a href="http://mdn.github.io/IDBcursor-example/" style="line-height: 1.5;">view example live</a><span style="line-height: 1.5;">.)</span></p>
<pre style="font-size: 14px;"><span style="line-height: 1.5;">function displayData() {</span>
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);
console.log(cursor.key);
cursor.continue();
} else {
console.log('Entries all displayed.');
}
};
};</pre>
<h2 id="规范">规范</h2>
<table class="standard-table">
<tbody>
<tr>
<th scope="col">规范</th>
<th scope="col">状态</th>
<th scope="col">说明</th>
</tr>
<tr>
<td>{{SpecName('IndexedDB', '#widl-IDBCursor-key', 'key')}}</td>
<td>{{Spec2('IndexedDB')}}</td>
<td> </td>
</tr>
<tr>
<td>{{SpecName("IndexedDB 2", "#dom-idbcursor-key", "key")}}</td>
<td>{{Spec2("IndexedDB 2")}}</td>
<td> </td>
</tr>
</tbody>
</table>
<h2 id="Browser_compatibility" name="Browser_compatibility">浏览器兼容性</h2>
<div>{{CompatibilityTable}}</div>
<div id="compat-desktop">
<table class="compat-table">
<tbody>
<tr>
<th>Feature</th>
<th>Chrome</th>
<th>Edge</th>
<th>Firefox (Gecko)</th>
<th>Internet Explorer</th>
<th>Opera</th>
<th>Safari (WebKit)</th>
</tr>
<tr>
<td>Basic support</td>
<td>23{{property_prefix("webkit")}}<br>
24</td>
<td>{{CompatVersionUnknown}}</td>
<td>10 {{property_prefix("moz")}}<br>
{{CompatGeckoDesktop("16.0")}}</td>
<td>10, partial</td>
<td>15</td>
<td>7.1</td>
</tr>
<tr>
<td>Available in workers</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{CompatGeckoDesktop("37.0")}}</td>
<td>{{CompatUnknown}}</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{CompatUnknown}}</td>
</tr>
<tr>
<td>Binary keys</td>
<td>{{CompatUnknown}}</td>
<td>{{CompatUnknown}}</td>
<td>{{CompatGeckoDesktop("51.0")}}</td>
<td>{{CompatUnknown}}</td>
<td>{{CompatUnknown}}</td>
<td>{{CompatUnknown}}</td>
</tr>
<tr>
<td>Indexed Database 2.0</td>
<td>{{CompatChrome(58)}}</td>
<td>{{CompatUnknown}}</td>
<td>{{CompatUnknown}}</td>
<td>{{CompatUnknown}}</td>
<td>{{CompatOpera(45)}}</td>
<td>{{CompatUnknown}}</td>
</tr>
</tbody>
</table>
</div>
<div id="compat-mobile">
<table class="compat-table">
<tbody>
<tr>
<th>Feature</th>
<th>Android Webview</th>
<th>Chrome for Android</th>
<th>Edge</th>
<th>Firefox Mobile (Gecko)</th>
<th>IE Phone</th>
<th>Opera Mobile</th>
<th>Safari Mobile</th>
</tr>
<tr>
<td>Basic support</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{CompatGeckoMobile("22.0")}}</td>
<td>10</td>
<td>22</td>
<td>8</td>
</tr>
<tr>
<td>Available in workers</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{CompatGeckoMobile("37.0")}}</td>
<td>{{CompatUnknown}}</td>
<td>{{CompatVersionUnknown}}</td>
<td>{{CompatUnknown}}</td>
</tr>
<tr>
<td>Binary keys</td>
<td>{{CompatUnknown}}</td>
<td>{{CompatUnknown}}</td>
<td>{{CompatUnknown}}</td>
<td>{{CompatGeckoMobile("51.0")}}</td>
<td>{{CompatUnknown}}</td>
<td>{{CompatUnknown}}</td>
<td>{{CompatUnknown}}</td>
</tr>
<tr>
<td>Indexed Database 2.0</td>
<td>{{CompatChrome(58)}}</td>
<td>{{CompatChrome(58)}}</td>
<td>{{CompatUnknown}}</td>
<td>{{CompatUnknown}}</td>
<td>{{CompatUnknown}}</td>
<td>{{CompatOperaMobile(45)}}</td>
<td>{{CompatUnknown}}</td>
</tr>
</tbody>
</table>
</div>
<h2 id="相关链接">相关链接</h2>
<ul>
<li><a href="/en-US/docs/Web/API/IndexedDB_API/Using_IndexedDB">Using IndexedDB</a></li>
<li>Starting transactions: {{domxref("IDBDatabase")}}</li>
<li>Using transactions: {{domxref("IDBTransaction")}}</li>
<li>Setting a range of keys: {{domxref("IDBKeyRange")}}</li>
<li>Retrieving and making changes to your data: {{domxref("IDBObjectStore")}}</li>
<li>Using cursors: {{domxref("IDBCursor")}}</li>
<li>Reference example: <a class="external" href="https://github.com/mdn/to-do-notifications/tree/gh-pages">To-do Notifications</a> (<a class="external" href="http://mdn.github.io/to-do-notifications/">view example live</a>.)</li>
</ul>
|
