The HTMLSelectElement.disabled Is a Boolean that reflects the disabled HTML attribute, which indicates whether the control is disabled. If it is disabled, it does not accept clicks. A disabled element is unusable and un-clickable.
The HTMLSelectElement.add() method adds an element to the collection of option elements for this select element.
The HTMLSelectElement.autofocus property is a Boolean that reflects the autofocus HTML attribute, which indicates whether the associated <select> element  will get input focus when the page loads, unless the user overrides it.
The HTMLSelectElement.form read-only property returns a HTMLFormElement representing the form that this element is associated with. If the element is not associated with of a <form> element, then it returns null.
The HTMLSelectElement.item() method returns the Element corresponding to the HTMLOptionElement whose position in the options list corresponds to the index given in parameter, or null if there are none.
The HTMLSelectElement.namedItem() method returns the HTMLOptionElement corresponding to the HTMLOptionElement whose name or id match the specified name, or null if no option matches.
The HTMLSelectElement.remove() method removes the element at the specified index from the options collection for this select element.
The HTMLSelectElement.checkValidity() method checks whether the element has any constraints and whether it satisfies them. If the element fails its constraints, the browser fires a cancelable invalid event at the element, and then returns false.
The HTMLSelectElement.selectedIndex is a long that reflects the index of the first selected <option> element. The value -1 indicates that no element is selected.
The HTMLSelectElement.setCustomValidity() method sets the custom validity message for the selection element to the specified message. Use the empty string to indicate that the element does not have a custom validity error.
The HTMLSelectElement.type read-only property returns the form control's type. The possible values are: