非标
此特征是非标准的，且不在标准轨道中。不要在面向 Web 的生产站点中使用它：它不适用于每个用户。实现之间可能存在大的不兼容性，且行为将来可能改变。
Obsolete since Gecko 7.0 (Firefox 7.0 / Thunderbird 7.0 / SeaMonkey 2.4)
This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.
Returns the name of the file. For security reasons the path is excluded from this property.
This property is deprecated. Use
File.name
代替。
var name = instanceOfFile.fileName;
A string
Not part of any specification.
File