How do you check if a string contains a substring case insensitive JavaScript?

The simplest way is to convert the entire string to either to lowercase or uppercase and use the javascript indexOf, includes methods as shown below. To check for case insensitive string contains, use the regular expressions. Add suffix “i” after the string regular expression as shown.

indexOf() methods are all case-sensitive .

Both String#includes() and String#indexOf() are case sensitive. Neither function supports regular expressions. To do case insensitive search, you can use regular expressions and the String#match() function, or you can convert both the string and substring to lower case using the String#toLowerCase() function .16 May 2019