---
title: Blob.size
slug: Web/API/Blob/size
tags:
  - API
  - Files
  - Property
  - Reference
  - WebAPI
  - 參考
  - 屬性
translation_of: Web/API/Blob/size
---
<div>{{APIRef("File API")}}</div>

<p><strong><code>Blob.size</code></strong> 屬性回傳以 byte 為單位的 {{domxref("Blob")}} 或一個 {{domxref("File")}} 的大小。</p>

<h2 id="語法">語法</h2>

<pre class="syntaxbox">var sizeInBytes = <em>blob</em>.size
</pre>

<h2 id="值">值</h2>

<p>一個數字。</p>

<h2 id="範例">範例</h2>

<pre class="brush:js">// fileInput 是個 HTMLInputElement: &lt;input type="file" multiple id="myfileinput"&gt;
var fileInput = document.getElementById("myfileinput");

// files 是個 FileList 物件 （類似 NodeList）
var files = fileInput.files;

for (var i = 0; i &lt; files.length; i++) {
  console.log(files[i].name + " has a size of " + files[i].size + " Bytes");
}</pre>

<h2 id="規格">規格</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">規格</th>
   <th scope="col">狀態</th>
   <th scope="col">附註</th>
  </tr>
  <tr>
   <td>{{SpecName('File API', '#dfn-size', 'size')}}</td>
   <td>{{Spec2('File API')}}</td>
   <td>初定義</td>
  </tr>
 </tbody>
</table>

<h2 id="瀏覽器相容性">瀏覽器相容性</h2>

<div>{{CompatibilityTable}}</div>

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>功能</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>File.size</td>
   <td>5</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatGeckoDesktop("2")}}</td>
   <td>10.0</td>
   <td>11.10</td>
   <td>5.1</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>功能</th>
   <th>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>File.size</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="參見">參見</h2>

<ul>
 <li>{{domxref("Blob")}}</li>
</ul>