Web/JavaScript/Reference/Errors/C* を更新

2021/03/29 時点の英語版に同期

1 files changed, 19 insertions, 16 deletions

diff --git a/files/ja/web/javascript/reference/errors/cant_access_property/index.html b/files/ja/web/javascript/reference/errors/cant_access_property/index.html
index b9bd300b79..a2fc8a56b4 100644
--- a/files/ja/web/javascript/reference/errors/cant_access_property/index.html
+++ b/files/ja/web/javascript/reference/errors/cant_access_property/index.html
@@ -2,38 +2,41 @@
 title: 'TypeError: can''t access property "x" of "y"'
 slug: Web/JavaScript/Reference/Errors/Cant_access_property
 tags:
-  - Error
-  - JavaScript
-  - TypeError
+- Error
+- Errors
+- JavaScript
+- TypeError
 translation_of: Web/JavaScript/Reference/Errors/Cant_access_property
 ---
 <div>{{jsSidebar("Errors")}}</div>
 
-<h2 id="メッセージ">メッセージ</h2>
+<p>JavaScript の例外 "can't access property" は、 {{jsxref("undefined")}} または {{jsxref("null")}} の値に対してプロパティのアクセスが行われた場合に発生します。</p>
 
-<pre class="syntaxbox">TypeError: Unable to get property {x} of undefined or null reference (Edge)
+<h2 id="Message">エラーメッセージ</h2>
+
+<pre class="brush: js">TypeError: Unable to get property {x} of undefined or null reference (Edge)
 TypeError: can't access property {x} of {y} (Firefox)
 TypeError: {y} is undefined, can't access property {x} of it (Firefox)
 TypeError: {y} is null, can't access property {x} of it (Firefox)
 
-Examples:
+例:
 TypeError: x is undefined, can't access property "prop" of it
 TypeError: x is null, can't access property "prop" of it
 TypeError: can't access property "prop" of undefined
 TypeError: can't access property "prop" of null
 </pre>
 
-<h2 id="エラータイプ">エラータイプ</h2>
+<h2 id="Error_type">エラーの種類</h2>
 
-<p>{{jsxref("TypeError")}}。</p>
+<p>{{jsxref("TypeError")}}</p>
 
-<h2 id="何がうまくいかなかったのか？">何がうまくいかなかったのか？</h2>
+<h2 id="What_went_wrong">エラーの原因</h2>
 
 <p>{{jsxref("undefined")}} か {{jsxref("null")}} に対してプロパティアクセスを行いました。</p>
 
-<h2 id="例">例</h2>
+<h2 id="Examples">例</h2>
 
-<h3 id="無効なケース">無効なケース</h3>
+<h3 id="Invalid_cases">無効な場合</h3>
 
 <pre class="brush: js example-bad">// undefined and null cases on which the substring method won't work
 var foo = undefined;
@@ -43,17 +46,17 @@ var foo = null;
 foo.substring(1); // TypeError: x is null, can't access property "substring" of it
 </pre>
 
-<h3 id="問題解決">問題解決</h3>
+<h3 id="Fixing_the_issue">問題の修正</h3>
 
-<p><code>undefined</code> か <code>null</code> の null pointer アクセスを修正するには、たとえば <a href="/ja/docs/Web/JavaScript/Reference/Operators/typeof">typeof</a> 演算子を使用できます。</p>
+<p><code>undefined</code> か <code>null</code> のヌルポインターアクセスを修正するには、たとえば <a href="/ja/docs/Web/JavaScript/Reference/Operators/typeof">typeof</a> 演算子を使用することができます。</p>
 
 <pre class="brush: js">if (typeof foo !== 'undefined') {
   // Now we know that foo is defined, we are good to go.
 }</pre>
 
-<h2 id="関連項目">関連項目</h2>
+<h2 id="See_also">関連情報</h2>
 
 <ul>
- <li>{{jsxref("undefined")}}</li>
- <li>{{jsxref("null")}}</li>
+  <li>{{jsxref("undefined")}}</li>
+  <li>{{jsxref("null")}}</li>
 </ul>