---
title: 定義済み関数
slug: Web/JavaScript/Guide/Predefined_Functions
---
<div class="onlyinclude">
  <h3 id=".E5.AE.9A.E7.BE.A9.E6.B8.88.E3.81.BF.E9.96.A2.E6.95.B0" name=".E5.AE.9A.E7.BE.A9.E6.B8.88.E3.81.BF.E9.96.A2.E6.95.B0">定義済み関数</h3>
  <p>JavaScript にはトップレベルの定義済み関数がいくつかあります。</p>
  <ul>
    <li><a href="/ja/Core_JavaScript_1.5_Guide/Predefined_Functions/eval_Function" title="ja/Core_JavaScript_1.5_Guide/Predefined_Functions/eval_Function">eval</a></li>
    <li><a href="/ja/Core_JavaScript_1.5_Guide/Predefined_Functions/isFinite_Function" title="ja/Core_JavaScript_1.5_Guide/Predefined_Functions/isFinite_Function">isFinite</a></li>
    <li><a href="/ja/Core_JavaScript_1.5_Guide/Predefined_Functions/isNaN_Function" title="ja/Core_JavaScript_1.5_Guide/Predefined_Functions/isNaN_Function">isNaN</a></li>
    <li><a href="/ja/Core_JavaScript_1.5_Guide/Predefined_Functions/parseInt_and_parseFloat_Functions" title="ja/Core_JavaScript_1.5_Guide/Predefined_Functions/parseInt_and_parseFloat_Functions">parseInt と parseFloat</a></li>
    <li><a href="/ja/Core_JavaScript_1.5_Guide/Predefined_Functions/Number_and_String_Functions" title="ja/Core_JavaScript_1.5_Guide/Predefined_Functions/Number_and_String_Functions">Number と String</a></li>
    <li><a href="/ja/Core_JavaScript_1.5_Guide/Predefined_Functions/escape_and_unescape_Functions" title="ja/Core_JavaScript_1.5_Guide/Predefined_Functions/escape_and_unescape_Functions">encodeURI と decodeURI、encodeURIComponent、decodeURIComponent（すべて Javascript 1.5 以降で使用可能）</a></li>
  </ul>
</div>
<p>{{ PreviousNext("JavaScript/Guide/Using_the_arguments_object", "JavaScript/Guide/Predefined_Functions/eval_Function") }}</p>