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Ilya Kantor 2017-09-24 08:58:52 +03:00
parent ab13ef8685
commit 0a2b936133
5 changed files with 41 additions and 34 deletions
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1-js/04-object-basics/01-object/article.md
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@ -222,7 +222,11 @@ obj.__proto__ = 5;
alert(obj.__proto__); // [object Object], didn't work as intended
```
As we see from the code, the assignment to a primitive `5` is ignored. If we want to store *arbitrary* (user-provided) keys, then such behavior can be the source of bugs and even vulnerabilities, because it's unexpected. There's another data structure [Map](info:map-set-weakmap-weakset), that we'll learn in the chapter <info:map-set-weakmap-weakset>, which supports arbitrary keys.
As we see from the code, the assignment to a primitive `5` is ignored.
That can be come a source of bugs and even vulnerabilies if we intent to store arbitrary key-value pairs in an object, and allow a visitor to specify the keys. In that case the visitor may choose "__proto__" as the key, and the assignment logic will be ruined (as shown above).
There's another data structure [Map](info:map-set-weakmap-weakset), that we'll learn in the chapter <info:map-set-weakmap-weakset>, which supports arbitrary keys. Also there's a way to make objects treat `__proto__` as a regular property, but first we need to know more about objects to understand it.
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