---
title: String.prototype.toLowerCase()
slug: Web/JavaScript/Reference/Global_Objects/String/toLowerCase
tags:
  - JavaScript
  - Method
  - Prototype
  - Reference
  - String
translation_of: Web/JavaScript/Reference/Global_Objects/String/toLowerCase
---
<div>{{JSRef}}</div>

<div><strong><code>toLowerCase()</code></strong> 메서드는 문자열을 소문자로 변환해 반환합니다.</div>

<div> </div>

<div>{{EmbedInteractiveExample("pages/js/string-tolowercase.html")}}</div>

<h2 id="구문">구문</h2>

<pre class="syntaxbox"><code><var>str</var>.toLowerCase()</code></pre>

<h3 id="반환값">반환값</h3>

<p>호출 문자열을 소문자로 변환한 새로운 문자열</p>

<h2 id="설명">설명</h2>

<p><code>toLowerCase()</code> 메서드는 호출 문자열을 소문자로 변환해 반환합니다.  <code>toLowerCase()</code> 는 원래의 <code>str</code>에 영향을 주지 않습니다.</p>

<h2 id="예제">예제</h2>

<h3 id="toLowerCase()"> <code>toLowerCase()</code></h3>

<pre class="brush: js">console.log('ALPHABET'.toLowerCase()); // 'alphabet'
</pre>

<h2 id="명세">명세</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">표준</th>
   <th scope="col">상태</th>
   <th scope="col">비고</th>
  </tr>
  <tr>
   <td>{{SpecName('ES1')}}</td>
   <td>{{Spec2('ES1')}}</td>
   <td>Initial definition. Implemented in JavaScript 1.0.</td>
  </tr>
  <tr>
   <td>{{SpecName('ES5.1', '#sec-15.5.4.16', 'String.prototype.toLowerCase')}}</td>
   <td>{{Spec2('ES5.1')}}</td>
   <td> </td>
  </tr>
  <tr>
   <td>{{SpecName('ES6', '#sec-string.prototype.tolowercase', 'String.prototype.toLowerCase')}}</td>
   <td>{{Spec2('ES6')}}</td>
   <td> </td>
  </tr>
  <tr>
   <td>{{SpecName('ESDraft', '#sec-string.prototype.tolowercase', 'String.prototype.toLowerCase')}}</td>
   <td>{{Spec2('ESDraft')}}</td>
   <td> </td>
  </tr>
 </tbody>
</table>

<h2 id="브라우저_호환성">브라우저 호환성</h2>

<p class="hidden">The compatibility table in 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>

<p>{{Compat("javascript.builtins.String.toLowerCase")}}</p>

<h2 id="참조">참조</h2>

<ul>
 <li>{{jsxref("String.prototype.toLocaleLowerCase()")}}</li>
 <li>{{jsxref("String.prototype.toLocaleUpperCase()")}}</li>
 <li>{{jsxref("String.prototype.toUpperCase()")}}</li>
</ul>