how to pass a variable in jquery

Question

I'm trying to pass a variable with name "myPassword" in function jquery but variable value in function return null.how to correct this?!

$(document).ready(function ($) {
    var myPassword = $('#facebox #myPassword:first').val();
    $(myPassword).strength({
        strengthClass: 'strength',
        strengthMeterClass: 'strength_meter',
        strengthButtonClass: 'button_strength',
        strengthButtonText: 'Show Password',
        strengthButtonTextToggle: 'Hide Password'
    });
});

Answer 1

Isn't it just the selector thats wrong (ie prepend with "."+ or "#" before)?

 var myPassword = $('#facebox #myPassword:first').val();
 $("." + myPassword).strength({ ...