What are the differences between JavaScript's String.indexOf() and String.includes()?

Ava W

In JavaScript, bothString.indexOf() andString.includes() are methods used to search for substrings within a string. However, they have some differences in functionality. Let's explore the differences between these two methods: 1. Return Value: -String.indexOf(): - TheindexOf() method returns the index of the first occurrence of the specified substring within the string. - If the substring is not found, it returns-1. -String.includes(): - Theincludes() method returns a boolean value indicating whether the string contains the specified substring. - It returnstrue if the substring is found, andfalse otherwise. 2. Usage: -String.indexOf(): - TheindexOf() method is commonly used when you need to know the index of the first occurrence of a substring within a string. - It is useful for tasks such as searching, extracting portions of a string, or checking for substring existence. -String.includes(): - Theincludes() method is used when you want to determine whether a string contains a particular substring. - It is more convenient for simple existence checks and does not require dealing with index values. 3. Case Sensitivity: -String.indexOf(): - By default, theindexOf() method performs a case-sensitive search. - You can use other methods, such astoLowerCase(), to make the search case-insensitive. -String.includes(): - Theincludes() method performs a case-sensitive search. - To make it case-insensitive, you can convert both the string and substring to lowercase or uppercase usingtoLowerCase() ortoUpperCase(). 4. Multiple Occurrences: -String.indexOf(): - TheindexOf() method finds the first occurrence of the substring. - If you need to find subsequent occurrences, you can use it in a loop or combine it with other methods. -String.includes(): - Theincludes() method only checks for the presence of the substring and does not provide information about subsequent occurrences. 5. Additional Parameters: -String.indexOf(): - TheindexOf() method accepts an optional second parameter,fromIndex, which specifies the starting index for the search. -String.includes(): - Theincludes() method does not accept any additional parameters. Consider the specific use case and requirements when choosing betweenindexOf() andincludes(). If you need the index of the substring or need to handle multiple occurrences,indexOf() is more suitable. If you only need to check for substring existence in a case-sensitive manner,includes() provides a more concise approach.