发布：2023/12/7 15:23:57作者：大数据 来源：大数据 浏览次数：409
sessionStorage 属性允许你访问一个 session Storage 对象。它与 localStorage 相似，不同之处在于 localStorage 里面存储的数据没有过期时间设置，而存储在 sessionStorage 里面的数据在页面会话结束时会被清除。页面会话在浏览器打开期间一直保持，并且重新加载或恢复页面仍会保持原来的页面会话。在新标签或窗口打开一个页面时会在顶级浏览上下文中初始化一个新的会话，这点和 session cookies 的运行方式不同。
应该注意，存储在sessionStorage或localStorage中的数据特定于该页面的协议。
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<span class="token comment">// 保存数据到 sessionStorage</span> sessionStorage<span class="token punctuation">.</span><span class="token function">setItem</span><span class="token punctuation">(</span><span class="token string">'key'</span><span class="token punctuation">,</span> <span class="token string">'value'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 从 sessionStorage 获取数据</span> <span class="token keyword">let</span> data <span class="token operator">=</span> sessionStorage<span class="token punctuation">.</span><span class="token function">getItem</span><span class="token punctuation">(</span><span class="token string">'key'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 从 sessionStorage 删除保存的数据</span> sessionStorage<span class="token punctuation">.</span><span class="token function">removeItem</span><span class="token punctuation">(</span><span class="token string">'key'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 从 sessionStorage 删除所有保存的数据</span> sessionStorage<span class="token punctuation">.</span><span class="token function">clear</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> |
一个 Storage 对象。
下面的代码访问当前域名的 session Storage 对象，并使用 Storage.setItem() 访问往里面添加一个数据条目。
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sessionStorage<span class="token punctuation">.</span><span class="token function">setItem</span><span class="token punctuation">(</span><span class="token string">'myCat'</span><span class="token punctuation">,</span> <span class="token string">'Tom'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> |
下面的示例会自动保存一个文本输入框的内容，如果浏览器因偶然因素被刷新了，文本输入框里面的内容会被恢复，因此写入的内容不会丢失。
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<span class="token comment">// 获取文本输入框</span> <span class="token keyword">var</span> field <span class="token operator">=</span> document<span class="token punctuation">.</span><span class="token function">getElementById</span><span class="token punctuation">(</span><span class="token string">"field"</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 检测是否存在 autosave 键值</span> <span class="token comment">// (这个会在页面偶然被刷新的情况下存在)</span> <span class="token keyword">if</span> <span class="token punctuation">(</span>sessionStorage<span class="token punctuation">.</span><span class="token function">getItem</span><span class="token punctuation">(</span><span class="token string">"autosave"</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token comment">// 恢复文本输入框的内容</span> field<span class="token punctuation">.</span>value <span class="token operator">=</span> sessionStorage<span class="token punctuation">.</span><span class="token function">getItem</span><span class="token punctuation">(</span><span class="token string">"autosave"</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token comment">// 监听文本输入框的 change 事件</span> field<span class="token punctuation">.</span><span class="token function">addEventListener</span><span class="token punctuation">(</span><span class="token string">"change"</span><span class="token punctuation">,</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token comment">// 保存结果到 sessionStorage 对象中</span> sessionStorage<span class="token punctuation">.</span><span class="token function">setItem</span><span class="token punctuation">(</span><span class="token string">"autosave"</span><span class="token punctuation">,</span> field<span class="token punctuation">.</span>value<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span> |
备注：完整的使用示例可以查看使用 Web Storage API一文。
| Specification | Status | Comment |
|---|---|---|
| Unknown sessionStorage |
Unknown |
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
|---|---|---|---|---|---|
| localStorage | 4 | 3.5 | 8 | 10.50 | 4 |
| sessionStorage | 5 | 2 | 8 | 10.50 | 4 |
各浏览器支持的 localStorage 和 sessionStorage 容量上限不同。测试页面 detailed rundown of all the storage capacities for various browsers。
Note: 从iOS 5.1之后，移动端的Safari将localStorage数据存储在cache文件中，在操作系统的要求下，会偶尔进行清除，特别是空间不足时。
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