javascript - 默认选择 Option Value 返回 Integer

Question

它有什么方法可以默认从 Select Option as Integer 获取值吗？

从这里选择

<select id="lesson_per_class" >
 <option value="">&nbsp;</option>
 <option value="1">1 Lesson</option>
 <option value="2">2 Lessons</option>
 <option value="3">3 Lessons</option>
 <option value="4">4 Lessons</option>
</select>

当我试图获取它们的值来计算时，我发现它返回为String，不能在这里计算

var lesson_per_class = $('#lesson_per_class').val();
alert('value is ' + ( 10 + lesson_per_class )); 
// it give result as 10x instead of 1x 

目前我解决的方法是parseInt()，但是我想知道，不管怎样，它有没有默认获取Integer？

Answer 1

从规范中您可以看到值是 DOMString所以不，默认情况下您无法获得整数。

http://www.w3.org/TR/html5/forms.html#the-option-element

For Java and ECMAScript, DOMString is bound to the String type because both languages also use UTF-16 as their encoding.

[NamedConstructor=Option(optional DOMString text = "", optional DOMString value, optional boolean defaultSelected = false, optional boolean selected = false)]
interface HTMLOptionElement : HTMLElement {
           attribute boolean disabled;
  readonly attribute HTMLFormElement? form;
           attribute DOMString label;
           attribute boolean defaultSelected;
           attribute boolean selected;
           attribute DOMString value;

           attribute DOMString text;
  readonly attribute long index;
};