regex - javascript includes() case insensitive

Question

I have an array of strings that I need to loop and check against with another passed in string.

var filterstrings = ['firststring','secondstring','thridstring'];
var passedinstring = localStorage.getItem("passedinstring");

for (i = 0; i < filterstrings.lines.length; i++) {
    if (passedinstring.includes(filterstrings[i])) {
        alert("string detected");
    }
}

How do I ensure that case sensitivity is ignored here (preferably by using regex) when filtering, if the var passedinstring were to have strings like FirsTsTriNg or fiRSTStrING?

Answer 1

You can create a RegExp from filterstrings first

var filterstrings = ['firststring','secondstring','thridstring'];
var regex = new RegExp( filterstrings.join( "|" ), "i");

then test if the passedinstring is there

var isAvailable = regex.test( passedinstring );