files/ja/web/api/performanceentry/tojson/index.html


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---
title: PerformanceEntry.toJSON()
slug: Web/API/PerformanceEntry/toJSON
tags:
  - API
  - Web パフォーマンス
  - メソッド
  - リファレンス
translation_of: Web/API/PerformanceEntry/toJSON
---
<div>{{APIRef("Performance Timeline API")}}</div>

<p><strong><code>toJSON()</code></strong> メソッドは<em>シリアライザ</em>で、{{domxref("PerformanceEntry","パフォーマンスエントリ")}}オブジェクトの JSON 表現を返します。</p>

<p>{{AvailableInWorkers}}</p>

<h2 id="構文">構文</h2>

<pre class="syntaxbox">json = perfEntry.toJSON();
</pre>

<h3 id="引数">引数</h3>

<dl>
 <dt>なし</dt>
 <dd> </dd>
</dl>

<h3 id="戻り値">戻り値</h3>

<dl>
 <dt>json</dt>
 <dd>{{domxref("PerformanceEntry")}} オブジェクトのシリアル化である JSON オブジェクト</dd>
</dl>

<h2 id="例">例</h2>

<p>次の例は、<code>toJSON()</code> メソッドの使用方法を示しています。</p>

<pre class="brush: js">function run_PerformanceEntry() {
  log("PerformanceEntry support ...");

  if (performance.mark === undefined) {
    log("... performance.mark Not supported");
    return;
  }

  // Create some performance entries via the mark() method
  performance.mark("Begin");
  do_work(50000);
  performance.mark("End");

  // Use getEntries() to iterate through the each entry
  var p = performance.getEntries();
  for (var i=0; i &lt; p.length; i++) {
    log("Entry[" + i + "]");
    check_PerformanceEntry(p[i]);
  }
}
function check_PerformanceEntry(obj) {
  var properties = ["name", "entryType", "startTime", "duration"];
  var methods = ["toJSON"];

  for (var i=0; i &lt; properties.length; i++) {
    // check each property
    var supported = properties[i] in obj;
    if (supported)
      log("..." + properties[i] + " = " + obj[properties[i]]);
    else
      log("..." + properties[i] + " = Not supported");
  }
  for (var i=0; i &lt; methods.length; i++) {
    // check each method
    var supported = typeof obj[methods[i]] == "function";
    if (supported) {
      var js = obj[methods[i]]();
      log("..." + methods[i] + "() = " + JSON.stringify(js));
    } else {
      log("..." + methods[i] + " = Not supported");
    }
  }
}
</pre>

<h2 id="仕様">仕様</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">仕様書</th>
   <th scope="col">ステータス</th>
   <th scope="col">コメント</th>
  </tr>
  <tr>
   <td>{{SpecName('Performance Timeline Level 2', '#dom-performanceentry-tojson', 'toJSON')}}</td>
   <td>{{Spec2('Performance Timeline Level 2')}}</td>
   <td><code>toJSON()</code> メソッドの初期定義</td>
  </tr>
 </tbody>
</table>

<h2 id="ブラウザの互換性">ブラウザの互換性</h2>

<div>
<p>{{Compat("api.PerformanceEntry.toJSON")}}</p>
</div>