[JQUERY] input value 가져오기 (by id, class, name)

<input type="hidden" id="test_id" class="test_class" name="test_name" value="test">

//1. Get a value by id
var value = $('#test_id').val();
//2. Get a value by class
var value = $('.test_class').val();
//3. Get a value by name
var value = $('input[name=test_name]').val();