How to use includes in js

The includes() method in JavaScript is used to check whether an array or string contains a specific element or substring. It starts the search at a specific position in the string or array, depending on the specified start argument. Returns true if found; false if not found.

Usage of includes() in JavaScript

What is includes()?

includes() is a built-in method in JavaScript that is used to determine whether a string or array contains a given substring or element.

Syntax

<code class="javascript">array.includes(element, start)
string.includes(substring, start)</code>

Where:

• array or string: to be checked Array or string.
• element or substring: The element or substring to be found.
• start (optional): Specify the position in the string or array to start searching (starting from 0).

Usage

Array

To check whether an array contains an element, you can use the following syntax:

<code class="javascript">const fruits = ["apple", "banana", "orange"];

console.log(fruits.includes("apple")); // true
console.log(fruits.includes("grape")); // false</code>

String

To check whether a string contains a certain substring, you can use the following syntax:

<code class="javascript">const message = "Hello, world!";

console.log(message.includes("world")); // true
console.log(message.includes("universe")); // false</code>

Optional The start Parameters The

start parameter allows you to specify where in a string or array to start searching. For example:

<code class="javascript">const fruits = ["apple", "banana", "orange", "apple"];

console.log(fruits.includes("apple", 2)); // true (从索引 2 开始查找)
console.log(message.includes("world", 6)); // false (从索引 6 开始查找)</code>

Return result

includes() method returns a Boolean value:

• true: If The specified element or substring was found.
• false: If the specified element or substring cannot be found.

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