40 lines
1.2 KiB
Markdown
40 lines
1.2 KiB
Markdown
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We can see which class it belongs by outputting it, like:
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```js run
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alert(document); // [object HTMLDocument]
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```
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Or:
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```js run
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alert(document.constructor.name); // HTMLDocument
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```
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So, `document` is an instance of `HTMLDocument` class.
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What's its place in the hierarchy?
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Yeah, we could browse the specification, but it would be faster to figure out manually.
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Let's traverse the prototype chain via `__proto__`.
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As we know, methods of a class are in the `prototype` of the constructor. For instance, `HTMLDocument.prototype` has methods for documents.
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Also, there's a reference to the constructor function inside the `prototype`:
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```js run
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alert(HTMLDocument.prototype.constructor === HTMLDocument); // true
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```
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To get a name of the class as a string, we can use `constructor.name`. Let's do it for the whole `document` prototype chain, till class `Node`:
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```js run
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alert(HTMLDocument.prototype.constructor.name); // HTMLDocument
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alert(HTMLDocument.prototype.__proto__.constructor.name); // Document
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alert(HTMLDocument.prototype.__proto__.__proto__.constructor.name); // Node
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```
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That's the hierarchy.
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We also could examine the object using `console.dir(document)` and see these names by opening `__proto__`. The console takes them from `constructor` internally.
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