如何在JavaScript中检查空Cookie？

Question

The following switch statement is not catching a cookie that does not exist.

switch (stateCookie) {
                    case 'Virginia':
                        window.location = '/Teacher-Login/VA';
                        break;
                    case 'North Carolina':
                        window.location = '/Teacher-Login/NC';
                        break;
                    case 'South Carolina':
                        window.location = '/Teacher-Login/SC';
                        break;
                    case null:
                        window.location = '/Teacher-Login/VA';
                        break;
                    case '':
                        window.location = '/Teacher-Login/VA';
                    default:
                        window.location = '/pages/state-login/login.html';

Ok, I have tried several things but I am still inexplicably having trouble with this. Here is the code that I have at this moment:

$('#welcome select').change(function () {
    var stateSelected = $('option:selected', this).val();
    var stateCookie = getCookie("ia_state");
    if(stateSelected != stateCookie)
    {
        setCookie('ia_state', stateSelected);
        switch (stateCookie) {
            case 'Virginia':
            case null:
            case '':
                window.location = '/Teacher-Login/VA';
                break;
            case 'North Carolina':
                window.location = '/Teacher-Login/NC';
                break;
            case 'South Carolina':
                window.location = '/Teacher-Login/SC';
                break;
            default:
                window.location = '/pages/state-login/login.html';
}
}
}); 

The switch statement is being evaluated but it is always going to the default case. I have yet to figure out how to catch it if the cookie is null/undefined.

Answer 1

You are missing a break:

                ...
                case '':
                    window.location = '/Teacher-Login/VA';
                    break;
                default:
                    window.location = '/pages/state-login/login.html';
                    break;

mdn has item function:

function hasItem(sKey) { 
    return (new RegExp("(?:^|;\\s*)" + escape(sKey).replace(/[\-\.\+\*]/g, "\\$&") + "\\s*\\=")).test(document.cookie); 
}  

Answer 2

I agree with Mike Stewart. You are missing a break, so if it's returning as '', then it will go on to the default statement. If you are still getting odd results after changing that, then it's possible the problem is somewhere else.

var loc = '';
switch (stateCookie) {
    case 'Virginia':
    case null:
    case '':
    case undefined:
        loc = '/Teacher-Login/VA';
        break;
    case 'North Carolina':
        loc = '/Teacher-Login/NC';
        break;
    case 'South Carolina':
        loc = '/Teacher-Login/SC';
        break;
    default:
        loc = '/pages/state-login/login.html';
        break;
};
window.location = loc;

EDIT: added undefined case

Answer 3

Something like:

if( $.cookie('cookiename') == null ) {
   /// is null
}

Answer 4

Validate your cookie before it enters in the switch, like:

stateCookie = (typeof stateCookie != 'string')?'':stateCookie;

Then the switch.

So, remove the case null from your switch.

case '':
    window.location = '/Teacher-Login/VA';