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+---
+title: BigInt
+slug: Web/JavaScript/Reference/Global_Objects/BigInt
+translation_of: Web/JavaScript/Reference/Global_Objects/BigInt
+---
+<p>{{JSRef}}{{SeeCompatTable}}</p>
+
+<p><code>BigInt</code> 是一個內建的物件，提供了表示大於2<sup>53</sup>的整數的功能 (2<sup>53</sup>是JavaScript原生的{{JSxRef("Number")}}能夠表示的最大值)</p>
+
+<h2 id="語法">語法</h2>
+
+<pre class="brush: js">BigInt(value);
+</pre>
+
+<h3 id="參數">參數</h3>
+
+<dl>
+ <dt><code>value</code></dt>
+ <dd>欲創建的數值，可以為整數或字串。</dd>
+</dl>
+
+<div class="blockIndicator note">
+<p><strong>Note</strong>: <code>BigInt()</code> 不和 {{JSxRef("Operators/new", "new")}} 一起使用。</p>
+</div>
+
+<dl>
+</dl>
+
+<h2 id="說明">說明</h2>
+
+<p><code>BigInt</code> 是透過在一個數值後加上 <code>n</code> ，例如 <code>10n</code> ，或呼叫 <code>BigInt()</code> 所生成的。</p>
+
+<pre class="brush: js">const theBiggestInt = 9007199254740991n;
+
+const alsoHuge = BigInt(9007199254740991);
+// ↪ 9007199254740991n
+
+const hugeString = BigInt("9007199254740991");
+// ↪ 9007199254740991n
+
+const hugeHex = BigInt("0x1fffffffffffff");
+// ↪ 9007199254740991n
+
+const hugeBin = BigInt("0b11111111111111111111111111111111111111111111111111111");
+// ↪ 9007199254740991n
+</pre>
+
+<p><code>BigInt</code> 跟 {{JSxRef("Number")}} 很像，但在某些部分有些許不同 — 它不可以被用在內建的 {{JSxRef("Math")}} 物件方法中、而且不可以跟 <code>Number</code> 的實體混用運算子。</p>
+
+<div class="blockIndicator warning">
+<p>{{JSxRef("Number")}} 和 <code>BigInt</code> 不能混和計算 — 他們必須被轉換到同一個型態。</p>
+
+<p>然而，在相互轉換時要注意， <code>BigInt</code> 在被轉換成 <code>Number</code> 時可能會遺失部分精度的資訊。</p>
+</div>
+
+<h3 id="類別資訊">類別資訊</h3>
+
+<p>當使用 <code>typeof</code> 測試時，一個 <code>BigInt</code> 會回傳 "bigint"：</p>
+
+<pre class="brush: js">typeof 1n === 'bigint'; // true
+typeof BigInt('1') === 'bigint'; // true
+</pre>
+
+<p>當使用 <code>Object</code> 來包裹時，<code>BigInt</code> 會被看成是普通的 "object" 型態：</p>
+
+<pre class="brush: js">typeof Object(1n) === 'object'; // true
+</pre>
+
+<h3 id="Operators">Operators</h3>
+
+<p>下列的運算子可以被用在 <code>BigInt</code> 上 (或由object包裹的 <code>BigInt</code>): <code>+</code>, <code>*</code>, <code>-</code>, <code>**</code>, <code>%</code>.</p>
+
+<pre class="brush: js">const previousMaxSafe = BigInt(Number.MAX_SAFE_INTEGER);
+// ↪ 9007199254740991
+
+const maxPlusOne = previousMaxSafe + 1n;
+// ↪ 9007199254740992n
+
+const theFuture = previousMaxSafe + 2n;
+// ↪ 9007199254740993n, this works now!
+
+const multi = previousMaxSafe * 2n;
+// ↪ 18014398509481982n
+
+const subtr = multi – 10n;
+// ↪ 18014398509481972n
+
+const mod = multi % 10n;
+// ↪ 2n
+
+const bigN = 2n ** 54n;
+// ↪ 18014398509481984n
+
+bigN * -1n
+// ↪ –18014398509481984n
+</pre>
+
+<p><code>/</code> 運算子也同樣的能夠運行。然而，因為型態是 <code>BigInt</code> 而不是 <code>BigDecimal</code> ，除法運算會無條件捨去小數。也就是說，回傳值不會包含小數部分。</p>
+
+<div class="blockIndicator warning">
+<p>回傳值帶小數的運算在使用<code>BigInt</code>  時小數部分會被捨去。</p>
+</div>
+
+<pre class="brush: js">const expected = 4n / 2n;
+// ↪ 2n
+
+const rounded = 5n / 2n;
+// ↪ 2n, not 2.5n
+
+</pre>
+
+<h3 id="比較">比較</h3>
+
+<p>一個 <code>BigInt</code> 並不嚴格等於一個 {{JSxRef("Global_Objects/Number", "Number")}}，但他們會一般相等。</p>
+
+<pre class="brush: js">0n === 0
+// ↪ false
+
+0n == 0
+// ↪ true</pre>
+
+<p>一個 {{JSxRef("Global_Objects/Number", "Number")}} 和 <code>BigInt</code> 可以像普通運算一樣比較。</p>
+
+<pre class="brush: js">1n &lt; 2
+// ↪ true
+
+2n &gt; 1
+// ↪ true
+
+2 &gt; 2
+// ↪ false
+
+2n &gt; 2
+// ↪ false
+
+2n &gt;= 2
+// ↪ true</pre>
+
+<p>他們可以參雜在陣列中並照預期的被排序。</p>
+
+<pre class="brush: js">const mixed = [4n, 6, -12n, 10, 4, 0, 0n];
+// ↪  [4n, 6, -12n, 10, 4, 0, 0n]
+
+mixed.sort();
+// ↪ [-12n, 0, 0n, 10, 4n, 4, 6]
+</pre>
+
+<p>Note that comparisons with <code>Object</code>-wrapped <code>BigInt</code>s act as with other objects, only indicating equality when the same object instance is compared:</p>
+
+<pre class="brush: js">0n === Object(0n); // false
+Object(0n) === Object(0n); // false
+
+const o = Object(0n);
+o === o // true
+</pre>
+
+<h3 id="Conditionals">Conditionals</h3>
+
+<p>A <code>BigInt</code> behaves like a {{JSxRef("Global_Objects/Number", "Number")}} in cases where it is converted to a {{JSxRef("Global_Objects/Boolean", "Boolean")}}: via the {{JSxRef("Global_Objects/Boolean", "Boolean")}} function; when used with logical operators {{JSxRef("Operators/Logical_Operators", "Logical Operators")}} <code>||</code>, <code>&amp;&amp;</code>, and <code>!</code>; or within a conditional test like an {{JSxRef("Statements/if...else", "if statement")}}.</p>
+
+<pre class="brush: js">if (0n) {
+  console.log('Hello from the if!');
+} else {
+  console.log('Hello from the else!');
+}
+
+// ↪ "Hello from the else!"
+
+0n || 12n
+// ↪ 12n
+
+0n &amp;&amp; 12n
+// ↪ 0n
+
+Boolean(0n)
+// ↪ false
+
+Boolean(12n)
+// ↪ true
+
+!12n
+// ↪ false
+
+!0n
+// ↪ true
+</pre>
+
+<h2 id="方法">方法</h2>
+
+<dl>
+ <dt>{{JSxRef("BigInt.asIntN()")}}</dt>
+ <dd>Wraps a BigInt between -2<sup>width-1</sup> and 2<sup>width-1</sup>-1</dd>
+ <dt>{{JSxRef("BigInt.asUintN()")}}</dt>
+ <dd>Wraps a BigInt between 0 and 2<sup>width</sup>-1</dd>
+</dl>
+
+<h2 id="屬性">屬性</h2>
+
+<dl>
+ <dt>{{JSxRef("BigInt.prototype")}}</dt>
+ <dd>允許對一個 <code>BigInt</code> 物件增加其屬性。</dd>
+</dl>
+
+<h2 id="BigInt_物件實體"><code>BigInt</code> 物件實體</h2>
+
+<p>All <code>BigInt</code> instances inherit from <code>BigInt.prototype</code>. The prototype object of the <code>BigInt</code> constructor can be modified to affect all <code>BigInt</code> instances.</p>
+
+<h3 id="方法_2">方法</h3>
+
+<p>{{page("/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt/prototype", "Methods")}}</p>
+
+<h2 id="建議用法">建議用法</h2>
+
+<h3 id="轉型">轉型</h3>
+
+<p>因為在 {{JSxRef("Global_Objects/Number", "Number")}} 和 <code>BigInt</code> 之間轉換可能造成精度遺失，建議當數值會超過2<sup>53</sup>時只使用 <code>BigInt</code> ，而不要在兩者之間進行轉換。</p>
+
+<h3 id="加密">加密</h3>
+
+<p><code>BigInt</code> 支援的運算並非常數時間。因此 <code>BigInt</code> <a href="https://www.chosenplaintext.ca/articles/beginners-guide-constant-time-cryptography.html">不適用在加密學上</a>。</p>
+
+<h2 id="範例">範例</h2>
+
+<h3 id="計算質數">計算質數</h3>
+
+<pre class="brush: js">function isPrime(p) {
+  for (let i = 2n; i * i &lt;= p; i++) {
+    if (p % i === 0n) return false;
+  }
+  return true;
+}
+
+// Takes a BigInt as an argument and returns a BigInt
+function nthPrime(nth) {
+  let maybePrime = 2n;
+  let prime = 0n;
+
+  while (nth &gt;= 0n) {
+    if (isPrime(maybePrime)) {
+      nth -= 1n;
+      prime = maybePrime;
+    }
+    maybePrime += 1n;
+  }
+
+  return prime;
+}
+
+nthPrime(20n)
+// ↪ 73n</pre>
+
+<h2 id="規範">規範</h2>
+
+<table class="standard-table">
+ <tbody>
+  <tr>
+   <th scope="col">規範</th>
+   <th scope="col">狀態</th>
+  </tr>
+  <tr>
+   <td><a href="https://tc39.github.io/proposal-bigint/#sec-bigint-objects">BigInt</a></td>
+   <td>Stage 3</td>
+  </tr>
+ </tbody>
+</table>
+
+<h2 id="瀏覽器相容性">瀏覽器相容性</h2>
+
+<div>
+
+
+<p>{{Compat("javascript.builtins.BigInt")}}</p>
+</div>
+
+<h2 id="另見">另見</h2>
+
+<ul>
+ <li>{{JSxRef("Number")}}</li>
+</ul>