What is case insensitive search?

A case-insensitive search is more comprehensive, finding “Language” (at the beginning of a sentence), “language”, and “LANGUAGE” (in a title in capitals ); a case-sensitive search will find the computer language “BASIC” but exclude most of the many unwanted instances of the word.

IndexOf Method is by default case sensitive . But we can make it case insensitive if we use one of the overloads: IndexOf(String, StringComparison).

To do a case insensitive check if an array contains a string in JavaScript: