Case insensitive contains(string)

Is there a way to make the following return true?

string title = "ASTRINGTOTEST";

title.Contains("string");

JavaScript: string contains

How can I check if one string contains another substring in JavaScript?

jQuery :contains selector to search for multiple strings

Assuming i have:

<li id="1">Mary</li>

<li id="2">John, Mary, Dave</li>

<li id="3">John, Dave, Mary</li>

<li id="4">John</li>