javascript - isPrototypeOf and __proto__ have different results -

the following 2 expressions:

"abc".__proto__.__proto__ === object.prototype  // true object.prototype.isprototypeof("abc")           // false 

the first expression proves object.prototype lies in prototype chain of "abc". however, second expression gets opposite result.

i confused. hope can explain.

"abc" not object. when evaluate "abc".__proto__, string wrapper object implicitly constructed retrieve prototype of, , object.prototype in wrapper object's prototype chain.

object.prototype.isprototypeof("abc") doesn't construct wrapper object. looks @ "abc", sees "abc" isn't object , has no prototype chain, , returns false. can see in ecmascript spec (version 6):

when isprototypeof method called argument v, following steps taken:

1. if type(v) not object, return false.

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