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---
title: String.prototype.substring()
slug: Web/JavaScript/Reference/Global_Objects/String/substring
translation_of: Web/JavaScript/Reference/Global_Objects/String/substring
---
<div>{{JSRef}}</div>
<p>The <strong><code>substring()</code></strong> method returns a subset of a <code>string</code> between one index and another, or through the end of the string.</p>
<h2 id="Syntax">Syntax</h2>
<pre class="syntaxbox"><code><var>str</var>.substring(<var>indexStart</var>[, <var>indexEnd</var>])</code></pre>
<h3 id="Parametreler">Parametreler</h3>
<dl>
<dt><code><var>indexStart</var></code></dt>
<dd>An integer between <code>0</code> and the length of the string, specifying the offset into the string of the first character to include in the returned substring.</dd>
<dt><code>indexEnd</code></dt>
<dd>Optional. An integer between <code>0</code> and the length of the string, which specifies the offset into the string of the first character <strong>not</strong> to include in the returned substring.</dd>
</dl>
<h3 id="Dönen_değer">Dönen değer</h3>
<p>A new string containing the extracted section of the given string.</p>
<h2 id="Açıklama">Açıklama</h2>
<p><code>substring()</code> extracts characters from <code>indexStart</code> up to <em>but not including</em> <code>indexEnd</code>. In particular:</p>
<ul>
<li>If <code><var>indexStart </var></code>equals <code><var>indexEnd</var></code>, <code>substring()</code> returns an empty string.</li>
<li>If <code>indexEnd</code> is omitted, <code>substring()</code> extracts characters to the end of the string.</li>
<li>If either argument is less than 0 or is {{jsxref("NaN")}}, it is treated as if it were 0.</li>
<li>If either argument is greater than <code>stringName.length</code>, it is treated as if it were <code>stringName.length</code>.</li>
</ul>
<p>If <code>indexStart</code> is greater than <code>indexEnd</code>, then the effect of <code>substring()</code> is as if the two arguments were swapped; for example, <code><em>str</em>.substring(1, 0) == <em>str</em>.substring(0, 1)</code>.</p>
<h2 id="Örnekler">Örnekler</h2>
<h3 id="Using_substring()">Using <code>substring()</code></h3>
<p>The following example uses <code>substring()</code> to display characters from the string <code>'Mozilla'</code>:</p>
<pre class="brush: js">var anyString = 'Mozilla';
// Displays 'Moz'
console.log(anyString.substring(0, 3));
console.log(anyString.substring(3, 0));
// Displays 'lla'
console.log(anyString.substring(4, 7));
console.log(anyString.substring(4));
console.log(anyString.substring(7, 4));
// Displays 'Mozill'
console.log(anyString.substring(0, 6));
// Displays 'Mozilla'
console.log(anyString.substring(0, 7));
console.log(anyString.substring(0, 10));
</pre>
<h3 id="Using_substring()_with_length_property">Using <code>substring()</code> with <code>length</code> property</h3>
<p>The following example uses the <code>substring()</code> method and {{jsxref("String.length", "length")}} property to extract the last characters of a particular string. This method may be easier to remember, given that you don't need to know the starting and ending indices as you would in the above examples.</p>
<pre class="brush: js">// Displays 'illa' the last 4 characters
var anyString = 'Mozilla';
var anyString4 = anyString.substring(anyString.length - 4);
console.log(anyString4);
// Displays 'zilla' the last 5 characters
var anyString = 'Mozilla';
var anyString5 = anyString.substring(anyString.length - 5);
console.log(anyString5);
</pre>
<h3 id="Replacing_a_substring_within_a_string">Replacing a substring within a string</h3>
<p>The following example replaces a substring within a string. It will replace both individual characters and substrings. The function call at the end of the example changes the string <code>'Brave New World'</code> into <code>'Brave New Web'</code>.</p>
<pre class="brush: js">// Replaces oldS with newS in the string fullS
function replaceString(oldS, newS, fullS) {
for (var i = 0; i < fullS.length; ++i) {
if (fullS.substring(i, i + oldS.length) == oldS) {
fullS = fullS.substring(0, i) + newS + fullS.substring(i + oldS.length, fullS.length);
}
}
return fullS;
}
replaceString('World', 'Web', 'Brave New World');
</pre>
<p>Note that this can result in an infinite loop if <code>oldS</code> is itself a substring of <code>newS</code> — for example, if you attempted to replace 'World' with 'OtherWorld' here. A better method for replacing strings is as follows:</p>
<pre class="brush: js">function replaceString(oldS, newS, fullS) {
return fullS.split(oldS).join(newS);
}
</pre>
<p>The code above serves as an example for substring operations. If you need to replace substrings, most of the time you will want to use {{jsxref("String.prototype.replace()")}}.</p>
<h2 id="Specifications">Specifications</h2>
<table class="standard-table">
<tbody>
<tr>
<th scope="col">Specification</th>
<th scope="col">Status</th>
<th scope="col">Comment</th>
</tr>
<tr>
<td>{{SpecName('ES1')}}</td>
<td>{{Spec2('ES1')}}</td>
<td>Implemented in JavaScript 1.0.</td>
</tr>
<tr>
<td>{{SpecName('ES5.1', '#sec-15.5.4.15', 'String.prototype.substring')}}</td>
<td>{{Spec2('ES5.1')}}</td>
<td> </td>
</tr>
<tr>
<td>{{SpecName('ES6', '#sec-string.prototype.substring', 'String.prototype.substring')}}</td>
<td>{{Spec2('ES6')}}</td>
<td> </td>
</tr>
<tr>
<td>{{SpecName('ESDraft', '#sec-string.prototype.substring', 'String.prototype.substring')}}</td>
<td>{{Spec2('ESDraft')}}</td>
<td> </td>
</tr>
</tbody>
</table>
<h2 id="Tarayıcı_uyumluluğu">Tarayıcı uyumluluğu</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.substring")}}</p>
<h2 id="Ayrıca_bakınız">Ayrıca bakınız</h2>
<ul>
<li>{{jsxref("String.prototype.substr()")}}</li>
<li>{{jsxref("String.prototype.slice()")}}</li>
</ul>
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