AutoComplete Mystery

Why does a select input field trigger autocomplete function without it being specifically named?

by w1djm

HTML

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
</head>
<body>
<p>
Start typing to search: <input type="search" id="ModSearch" placeholder="Start typing to search">

<section>
You may refine your search by choosing a county
<select name="county" id="county" size="1">
<option value="">-- Select County --</option>
<option value="91">ABC</option>
<option value="92">DEF</option>
<option value="93">XYZ</option>
</select>
</section>
<div id="results" style="display: none;"></div>
</body>
</html>

JavaScript

function AutoComplete() {

	$("#ModSearch,#county").autocomplete({
		source: function(request, response) {

			var look4   = $("#ModSearch").val();
			var county  = $("#county").val();

			var request = $.ajax({
					url: 'SO_Question.php',
					data: { look4   : look4    ,
						    county  : county}  ,
					dataType: "text",
					cache: false
					})

			request.done(function( response ) {

				document.getElementById('results').innerHTML     = response;
				document.getElementById("results").style.display = "block";

			});

		},  // end of source

	});  // end of autocomplete

}  // end of the AutoComplete function

$(function() {

	$('#ModSearch').on('input',function() {
		AutoComplete();
	});

});  // end of function