Seamless Digital Experience.
Happy Customers.

Digital Experience and Error Monitoring Platform - Zipy

How to Check If a String Contains a Substring in JavaScript: An In-Depth Tutorial

Anchal Rastogi
~ 5 min read | Published on Apr 12, 2024


Fix bugs faster with Zipy!

  • Session replay
  • Network calls
  • Console Logs
  • Stack traces
  • User identification
Get Started for Free

Understanding Strings in JavaScript

Strings in JavaScript are used to store and manipulate text. They can be anything from letters, numbers, to symbols, encapsulated within either single quotes ('), double quotes ("), or template literals (`), the latter allowing for multi-line strings and string interpolation. In web development, strings play a critical role, whether you're working with user inputs, API responses, or manipulating DOM elements. Knowing how to handle strings efficiently can lead to cleaner code, better performance, and an overall more effective coding practice.

Debug and fix code errors with Zipy Error Monitoring.

Get Started for Free

Methods to Check if a String Contains a Substring

JavaScript provides several methods to determine whether a string contains a specific sequence of characters. Understanding these methods is crucial for string manipulation and data validation tasks.

includes() Method

The includes() method determines if one string may be found within another string, returning true or false as appropriate.


str.includes(searchString, position)
  • searchString: The substring to search for.
  • position: The position within the string at which to begin searching for searchString. (Optional; default is 0.)


const sentence = "The quick brown fox jumps over the lazy dog.";
const word = "fox";

console.log(sentence.includes(word)); // Output: true


In this example, includes() checks if the word "fox" is present in our sentence. It returns true since "fox" is indeed part of the sentence.

indexOf() Method

The indexOf() method returns the index of the first occurrence of the specified value, or -1 if it is not found.


str.indexOf(searchValue, fromIndex)
  • searchValue: The substring to search for in the string.
  • fromIndex: The index to start the search at. If omitted, the search starts at the beginning of the string.


const sentence = "Hello world, welcome to the universe.";
const word = "welcome";

console.log(sentence.indexOf(word)); // Output: 13


Here, indexOf() is used to find the position of the word "welcome" in the sentence. It returns 13, indicating the starting index of the substring.

search() Method

The search() method executes a search for a match between a regular expression and this String object.

  • regexp: A regular expression object. If a non-RegExp object obj is passed, it is implicitly converted to a RegExp by using new RegExp(obj).


const sentence = "Let's find where 'find' occurs!";
const regex = /find/;

console.log(; // Output: 6


This example demonstrates using search() with a regular expression to find the position of the word "find" in the sentence, which is at index 6.

Using Regular Expressions

Regular expressions (Regex) are patterns used to match character combinations in strings. In JavaScript, regex can be used with the match(), replace(), search(), and split() methods to conduct advanced search and replace operations.


const sentence = "Regex is great for pattern matching.";
const pattern = /great/;

console.log(pattern.test(sentence)); // Output: true


Here, test() is a RegExp method that checks if the pattern exists within the sentence, returning true because the pattern "great" is found.

Tips for Effective String Search

  • Case Sensitivity: Remember, all these methods are case-sensitive. To perform a case-insensitive search, you can convert the string and the search string to the same case (either to lower case or upper case) before searching.
  • Multiple Occurrences: If you need to find multiple occurrences of a substring, you can use the match() method with a global regular expression.
  • Performance: For large strings or complex searches, consider the performance implications of each method. Regular expressions can be powerful but may impact performance negatively if not used wisely.

Debug and fix code errors with Zipy Error Monitoring.

Get Started for Free

Integrating Advanced Monitoring Tools

In today's fast-paced web development environment, efficient debugging and error handling are pivotal. Tools that offer real-time monitoring and error logging can significantly ease the development process. Zipy's advanced monitoring tool, with its innovative session replay capabilities, provides an invaluable resource for developers. It not only identifies errors but also helps in understanding the user's journey leading up to the error. This level of insight can drastically reduce debugging time and improve overall application quality.

For developers looking to enhance their debugging toolkit, integrating a solution like Zipy can be a game-changer. Discover more about how Zipy can transform your error handling approach by visiting Zipy's session replay tool.

This article has walked you through several methods to check if a string contains a substring in JavaScript, providing you with the tools to handle string manipulations effectively. Whether you're validating user inputs, searching through large datasets, or simply manipulating strings for various web development tasks, these methods form the cornerstone of efficient JavaScript programming. With the addition of advanced tools like Zipy, developers can further streamline their workflow, ensuring robust and error-free applications.

Read more resources Javascript concepts

Call to Action

Feel free to comment or write to us in case you have any further questions at We would be happy to help you. In case you want to explore for your app, you can sign up or book a demo.

Fix bugs faster with Zipy!

Get Started for Free

You might also like

Wanna try Zipy?

Zipy provides you with full customer visibility without multiple back and forths between Customers, Customer Support and your Engineering teams.

The unified digital experience platform to drive growth with Product Analytics, Error Tracking, and Session Replay in one.

SOC 2 Type 2
Zipy is GDPR and SOC2 Type II Compliant
© 2023 Zipy Inc. | All rights reserved
by folks just like you
// open links in new tab script