How to get the value of the current select element

1. If all option elements under the select element do not specify the selected attribute, the first one will be selected by default.
2. The index of the selected option element can be obtained through select.selectedIndex.
3. The selected option element can be obtained through select.options[select.selectedIndex].
4. option element <option selected="selected" value="value3">text3</option>, the value attribute value of the option element can be obtained through option.value, that is, value3; the text within the option element can be obtained through option.text, that is, text3.
5. If the option element does not define a value attribute, option.value cannot be obtained in IE, but Safari, Opera, and FireFox can still obtain it through option.value, and the value is the same as option.text.
6. You can use option.attributes.value && option.attributes.value.specified to determine whether the option element defines the value attribute.

Therefore, the script to obtain the current select element value is as follows:

var getSelectValue = function(select) {
var idx = select.selectedIndex,
option,
value;
if (idx > -1) {
option = select.options[idx];
value = option.attributes.value;
return (value && value.specified) ? option.value : option.text);
}
return null;
}