Checking if a string does not include substrings is one of the most common tasks in any programming language. In Javascript, users can manipulate many different ways to achieve their goals. In this article, we will show you the three simplest and most commonly used methods to Check if String Doesn’t include Substring. Let’s find out together!

How to check if string doesn’t include substring in JavaScript

We will have three commonly used ways to check if string doesn’t include Substring in JavaScript as follows:

• Use the includes() function
• Use the indexOf() function
• Use the “logical NOT (!)” operator

Let’s follow the specific steps below.

Method 1: using the includes() function

This is the simplest and most basic method to check if a string includes a substring or not. This method is compatible with most browsers, except Internet Explorer, so users can easily use it.

Syntax:

includes(searchString)

includes(searchString, position)

“searchString” is a string you need to search for in “str”, “position” is the string position and usually defaults to 0.

The result returned when running the syntax is True if it contains the string and False if it does not.

Here is an example to make it easier for you to visualize:

Code sample

const str = 'Check if string doesn’t include substring in JavaScript'
console.log(str.includes('JavaScript')) 

Output

true

Code sample

const str = 'Check if string doesn’t include substring in JavaScript'
console.log(str.includes('python'))

Output

false

Method 2: Using the “logical NOT (!)” operator

In simple terms, this will be the negative method of the includes() function. As you know, in the above method, if a string contains no substrings, includes() will return False. However, with the use of the logical NOT (!) operator, the result will be the opposite, which means that if the string does not contain a substring, the return result will be True.

Here is a specific example:

const str = 'IT tutoria';

// Use the includes() function
console.log(str.includes('tutorial')); // false

// Use the logical NOT (!) operator
console.log(!str.includes('tutorial')); // true

Method 3: Using the indexOf() function

If your browser cannot use the above two methods, you can consider using this 3rd method. With the indexOf() function, the result returned will be related to the index of the string, so you need to understand the theory of indexes.

Syntax:

indexOf(searchString)

indexOf(searchString, position)

Similarly, searchString is the Substring to search, and the position will default to 0. 

For instance:

var string = "tutoria"; 
var substring = "ria";
console.log(string.indexOf(substring) !== -1); // true

This function will return the result as the first occurrence of the string (starting at position 0); if the string is not found, it will return -1. If the Substring is found, it returns the index of the character that started the string. 

Conclusion

To summarize, the above ITtutoria have helped you better understand the topic “How to check if string doesn’t include substring in JavaScript” and some methods to handle it. If you have any questions, please leave a comment for us to be able to assist you as soon as possible. Thanks for reading!