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author | Peter Bengtsson <mail@peterbe.com> | 2020-12-08 14:40:17 -0500 |
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committer | Peter Bengtsson <mail@peterbe.com> | 2020-12-08 14:40:17 -0500 |
commit | 33058f2b292b3a581333bdfb21b8f671898c5060 (patch) | |
tree | 51c3e392513ec574331b2d3f85c394445ea803c6 /files/zh-cn/web/javascript/reference/global_objects/arraybuffer/index.html | |
parent | 8b66d724f7caf0157093fb09cfec8fbd0c6ad50a (diff) | |
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diff --git a/files/zh-cn/web/javascript/reference/global_objects/arraybuffer/index.html b/files/zh-cn/web/javascript/reference/global_objects/arraybuffer/index.html new file mode 100644 index 0000000000..a98aca4290 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/arraybuffer/index.html @@ -0,0 +1,161 @@ +--- +title: ArrayBuffer +slug: Web/JavaScript/Reference/Global_Objects/ArrayBuffer +tags: + - ArrayBuffer + - JavaScript + - 构造函数 + - 类型数组 +translation_of: Web/JavaScript/Reference/Global_Objects/ArrayBuffer +--- +<div> +<p>{{JSRef}}</p> + +<p><strong><code>ArrayBuffer</code></strong> 对象用来表示通用的、固定长度的原始二进制数据缓冲区。</p> + +<p>它是一个字节数组,通常在其他语言中称为“byte array”。</p> + +<p>你不能直接操作 <code>ArrayBuffer</code> 的内容,而是要通过<a href="https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/TypedArray">类型数组对象</a>或 {{jsxref("DataView")}} 对象来操作,它们会将缓冲区中的数据表示为特定的格式,并通过这些格式来读写缓冲区的内容。</p> +</div> + +<div>{{EmbedInteractiveExample("pages/js/arraybuffer-constructor.html")}}</div> + + + +<h2 id="语法">语法</h2> + +<pre class="syntaxbox notranslate">new ArrayBuffer(length) +</pre> + +<h3 id="参数">参数</h3> + +<dl> + <dt><code>length</code></dt> + <dd>要创建的 <code>ArrayBuffer</code> 的大小,单位为字节。</dd> +</dl> + +<h3 id="返回值">返回值</h3> + +<p>一个指定大小的 <code>ArrayBuffer</code> 对象,其内容被初始化为 0。</p> + +<h3 id="异常">异常</h3> + +<p>如果 <font face="consolas, Liberation Mono, courier, monospace"><span style="background-color: rgba(220, 220, 220, 0.5);">length</span></font> 大于 {{jsxref("Number.MAX_SAFE_INTEGER")}}(>= 2 ** 53)或为负数,则抛出一个 {{jsxref("RangeError")}} 异常。</p> + +<h2 id="描述">描述</h2> + +<p><code>ArrayBuffer</code> 构造函数用来创建一个指定字节长度的 <code>ArrayBuffer</code> 对象。</p> + +<h3 id="以现有数据获取_ArrayBuffer">以现有数据获取 ArrayBuffer</h3> + +<ul> + <li><a href="https://developer.mozilla.org/zh-CN/docs/Web/API/WindowBase64/Base64_encoding_and_decoding#Appendix.3A_Decode_a_Base64_string_to_Uint8Array_or_ArrayBuffer">从 Base64 字符串</a></li> + <li><a href="https://developer.mozilla.org/zh-CN/docs/Web/API/FileReader#readAsArrayBuffer()">从本地文件</a></li> +</ul> + +<h2 id="属性">属性</h2> + +<dl> + <dt><code>ArrayBuffer.length</code></dt> + <dd>ArrayBuffer 构造函数的 length 属性,其值为1。</dd> +</dl> + +<dl> + <dt>{{jsxref("ArrayBuffer.prototype.byteLength")}}</dt> + <dd>只读属性,表示 <code>ArrayBuffer</code> 的byte的大小,在ArrayBuffer构造完成时生成,不可改变。</dd> +</dl> + +<dl> + <dt>{{jsxref("ArrayBuffer.@@species", "get ArrayBuffer[@@species]")}}</dt> + <dd>返回 ArrayBuffer 的构造函数。</dd> + <dt>{{jsxref("ArrayBuffer.prototype")}}</dt> + <dd>通过 ArrayBuffer 的原型对象可以为所有 ArrayBuffer 对象添加属性。</dd> +</dl> + +<h2 id="方法">方法</h2> + +<dl> + <dt>{{jsxref("ArrayBuffer.isView", "ArrayBuffer.isView(arg)")}}</dt> + <dd>如果参数是 ArrayBuffer 的视图实例则返回 <code>true</code>,例如 <a href="https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/TypedArray">类型数组对象</a> 或 {{jsxref("DataView")}} 对象;否则返回 <code>false</code>。</dd> + <dt>{{jsxref("ArrayBuffer.transfer", "ArrayBuffer.transfer(oldBuffer [, newByteLength])")}} {{experimental_inline}}</dt> + <dd> + <p>返回一个新的 ArrayBuffer 对象,其内容取自 <code>oldBuffer</code> 中的数据,并且根据 <code>newByteLength</code> 的大小对数据进行截取或补 0。</p> + </dd> +</dl> + +<h2 id="ArrayBuffer_实例">ArrayBuffer 实例</h2> + +<p>所有 <code>ArrayBuffer</code> 实例都会从 {{jsxref("ArrayBuffer.prototype")}} 继承属性和方法。</p> + +<h3 id="属性_2">属性</h3> + +<p>{{page('zh-CN/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer/prototype','属性')}}</p> + +<h3 id="方法_2">方法</h3> + +<p>{{page('zh-CN/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer/prototype','方法')}}</p> + +<dl> + <dt>{{jsxref("ArrayBuffer.slice()")}} {{non-standard_inline}}</dt> + <dd>和 {{jsxref("ArrayBuffer.prototype.slice()")}} 功能相同。</dd> +</dl> + +<h2 id="示例">示例</h2> + +<p>下面的例子创建了一个 8 字节的缓冲区,并使用一个 {{jsxref("Global_Objects/Int32Array", "Int32Array")}} 来引用它:</p> + +<pre class="notranslate"><code>var buffer = new ArrayBuffer(8); +var view = new Int32Array(buffer);</code> +</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">Specification</th> + <th scope="col">Status</th> + <th scope="col">Comment</th> + </tr> + <tr> + <td>{{SpecName('Typed Array')}}</td> + <td>{{Spec2('Typed Array')}}</td> + <td>已被 ECMAScript 6 中的 ArrayBuffer 取代</td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-arraybuffer-constructor', 'ArrayBuffer')}}</td> + <td>{{Spec2('ES6')}}</td> + <td>在 ECMA 标准中的初始定义。规定了必须通过 <code>new</code> 来调用构造函数</td> + </tr> + <tr> + <td>{{SpecName('ESDraft', '#sec-arraybuffer-constructor', 'ArrayBuffer')}}</td> + <td>{{Spec2('ESDraft')}}</td> + <td></td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<div class="hidden"> +<p>The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out <a href="https://github.com/mdn/browser-compat-data">https://github.com/mdn/browser-compat-data</a> and send us a pull request.</p> +</div> + +<p>{{Compat("javascript.builtins.ArrayBuffer")}}</p> + +<h2 id="兼容性提醒">兼容性提醒</h2> + +<p>从 ECMAScript 2015 开始,<code>ArrayBuffer</code> 对象需要用 {{jsxref("Operators/new", "new")}} 运算符创建。如果调用构造函数时没有使用 <code>new</code>,将会抛出 {{jsxref("TypeError")}} 异常。</p> + +<pre class="brush: js example-bad notranslate">var dv = ArrayBuffer(10); +// TypeError: calling a builtin ArrayBuffer constructor +// without new is forbidden</pre> + +<pre class="brush: js example-good notranslate">var dv = new ArrayBuffer(10);</pre> + +<h2 id="相关链接">相关链接</h2> + +<ul> + <li><a href="https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Typed_arrays">JavaScript 类型数组</a></li> + <li><a href="zh-CN/docs/Web/JavaScript/Typed_arrays" title="zh-CN/JavaScript typed arrays">{{jsxref("SharedArrayBuffer")}}</a></li> +</ul> |