How to make a webpage read-only (disable input) with jQuery.

$("input:button").attr("disabled", true);  // Disables all buttons
$("input:text").attr("disabled", true);
$("input:checkbox").attr("disabled", true);
$('#myCustomElement').attr("disabled", true);

Some extra css to gray out elements can be usefull too.

Add option to html dropdownlist with jQuery

$('#dropdownId').append($('<option>', {
                    value: value,
                    text: text ,
                    selected: true
}));

// Not selected option 

$('#dropdownId').append($('<option>', {
                    value: value,
                    text: text                  
}));