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Table of Contents
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<title>JavaScript String Splitting: substring() vs. split()</title>
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<h1>JavaScript String Splitting: `substring()` vs. `split()`</h1>
<p>JavaScript offers two primary methods for dividing strings into substrings: `substring()` and `split()`. Each serves a distinct purpose.</p>
<h2>`substring()`</h2>
<p>The `substring()` method extracts a portion of a string based on starting and ending indices. It's ideal for retrieving a single substring from a known position within the string.</p>
<p><strong>Syntax:</strong> <code>string.substring(startIndex, endIndex)</code></p>
<ul>
<li><code>startIndex</code>: The index of the first character to include (0-based).</li>
<li><code>endIndex</code> (optional): The index *after* the last character to include. If omitted, the substring extends to the end of the string.</li>
</ul>
<p><strong>Example:</strong></p>
<pre class="brush:php;toolbar:false"><code>
const str = "Hello, world!";
const sub = str.substring(7, 12); // Extracts "world"
console.log(sub); // Output: "world"
Often, you'll use `indexOf()` to dynamically determine the start or end indices.
`split()`
The `split()` method divides a string into an array of substrings based on a specified separator. This is perfect for handling strings containing lists of items delimited by a character (e.g., comma-separated values).
Syntax: string.split(separator, limit)
separator: The character or string used to divide the string.limit(optional): The maximum number of substrings to return.
Example:
<code>
const csv = "apple,banana,cherry";
const fruits = csv.split(","); // Splits at each comma
console.log(fruits); // Output: ["apple", "banana", "cherry"]
</code>
Key Differences
| Feature | `substring()` | `split()` |
|---|---|---|
| Output | Substring (string) | Array of substrings |
| Purpose | Extract a portion at specific indices | Split into multiple substrings based on a separator |
| Index-based | Yes | No (separator-based) |
When to Use Each Method
- Use `substring()` when you need to extract a single, continuous piece of text from a known position within the string.
- Use `split()` when you need to break a string into multiple parts based on a delimiter, such as commas, spaces, or other characters.
