Question

I get that error with the following code. anyone know why?

function validateAdminInput(){
    var mandFields = $('.mand');

    for(i=0; i< mandFields.length;i++){
        if (mandFields[i].value == ""){
            mandFields[i].css('border','solid red 1px');
        }
    }
}

Answer 1

mandFields[i] gives you the underlying DOM element. You need to wrap it in a $(mandFields[i]) if you want to access the jQuery .css() function.

Or:

function validateAdminInput() {
    $('.mand').each(function() {
        if ($(this).val() == '') {
            $(this).css('border','solid red 1px');
        }
    });
}

or even:

function validateAdminInput() {
    $('.mand[value=""]').css('border','solid red 1px');
}