as to your code,

B as a function has an own property named "prototype". B.prototype.constructor is B. This is the default behavior.

ln#11 and ln#12 attempts to change the default and should always come together in that:
ln#11 changes B's prototype; and if you changes B's prototype to C, you should set C's own property "constructor" to B. In this way you can avoid a pervert case that a consturctor(X)'s constructed object's constructor(not own but inherited) is not X.


【 在 xiatianup (李 ，只是期待夏天！！) 的大作中提到: 】
: 根据说法1，它应当指向A，因为第11行表明了原型B的一切从A继承（从new A创建的原型B的内容）而来。
: 根据说法2，原型B的constructor应当指向它自己，B。
: 那这2个说法显然是有点冲突啊。
: ...................
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修改:a0123456789q FROM 183.95.135.*
FROM 183.95.135.*