javascript - How to check an entire string if it contains a specific word using jQuery?

I need help on checking a certain word if it contains in a
string that is being assigned into my input textbox.
For example below, If
there's a string value assigned to this
textbox

            id="StartLocation" name="StartLocation" value="1 AAC, MT SECTION, RAF SCAMPTON, LINCOLN,
            LN1 2ST, UNITED KINGDOM"
            >

I want
to check if it contains the word "UNITED KINGDOM" and if
does not, it should return false.
I tried something like this below but it
keeps returning true because the alert message is always 'It contains United Kingdom'
even though I already
change the value.

if
            ($("input#StartLocation:contains('UNITED KINGDOM')")) {
 alert('It contains
            United Kingdom');
} else {
 alert('It does not contains United
            Kingdom');
}

How
do I fix this? Thanks...