枚舉屬性可以定義爲具有有效值列表:例如,
以及兩個默認
然後一個元素foo
和上述屬性bar
:
<foo bar="date"> => valid value, state is `date`
<foo bar="time"> => invalid value, state is the invalid default `phone`
<foo> => missing value, state is the missing value default `text`
然而有時,屬性並沒有爲它定義一個無效的默認,但它確實有一個缺失值默認定義。在這種情況下:
<foo bar="date"> => valid value, state is `date`
<foo bar="time"> => invalid value, state is the missing value default `text`
<foo> => missing value, state is the missing value default `text`
有時屬性具有爲它定義一個無效的默認,但它並沒有缺失值默認定義。在這種情況下:
<foo bar="date"> => valid value, state is `date`
<foo bar="time"> => invalid value, state is the invalid default `phone`
<foo> => missing value, attribute has no state
有時該屬性沒有爲其定義的無效缺省值或缺省值缺省值。在這種情況下:
<foo bar="date"> => valid value, state is `date`
<foo bar="time"> => invalid value, attribute has no state
<foo> => missing value, attribute has no state
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