Checking if a String Contains a Substring in JavaScript: indexOf() and includes() Methods

When it comes to checking if a string contains a specific substring, developers often rely on two built-in JavaScript methods: `indexOf()` and `includes()`. In this article, we'll delve into the syntax breakdown of these methods and explore how to use them effectively.

Using the `indexOf()` Method

The `indexOf()` method is used to retrieve the index (or position) of a specified value within a string. It returns the index of the first occurrence of the specified value or -1 if not found. Here's the syntax:

```javascript

string.indexOf(substring, 'start')

```

The `'start'` parameter is optional and specifies the starting point for the search. For example, `myString.indexOf('word', 5)` would start searching from the sixth character.

Let's consider an example:

```javascript

var myString = 'Hello World';

console.log(myString.indexOf('World')); // Output: 6

```

In this case, the output is 6 because the substring 'World' starts at the seventh position (remember that indices in JavaScript are zero-based).

Using the `includes()` Method

The `includes()` method returns a boolean value indicating whether a specified value exists within a string or not. Here's the syntax:

```javascript

string.includes(substring)

```

This method is more straightforward than `indexOf()`, as it simply returns `true` if the substring is found and `false` otherwise.

Here's an example:

```javascript

var myString = 'Hello World';

console.log(myString.includes('World')); // Output: true

```

In this case, the output is `true` because the substring 'World' exists within the string.

In this article, we've explored two ways to check if a string contains a specific substring using JavaScript methods. The `indexOf()` method returns the index of the specified value or -1 if not found, while the `includes()` method simply returns a boolean value indicating whether the substring exists within the string. By mastering these methods, you'll be equipped to tackle various tasks involving string manipulation in your JavaScript projects.

Js string includes