var dom = document.getElementById('domId');
dom.innerHTML = "hello world!";
console.log(typeof dom); //object
console.log(dom.hasOwnProperty("innerHTML")); //false
console.log(dom.__proto__.hasOwnProperty("innerHTML")); //false
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認(rèn)證高級(jí)PHP講師
typeof can only roughly identify object or other basic data types. You might as well try toString. I have seen some framework js and check the object type through toString. Perform string processing on the result to get the type name. .
You can check related content in mdn, such as p’s dom type https://developer.mozilla.org...
You can see its main inheritance relationship.
For example innerHTML, actually here https://developer.mozilla.org...
Attributes of the Element class
As you can see from the picture above, HTML elements have corresponding interfaces, which are part of javasript. Please refer to MDN
https://developer.mozilla.org...
The prototype chain is HTMLpElement -> HTMLELement -> Element -> Node -> EventTarget
but innerHTML cannot be used directly on them, 
The innerHTML assignment/retrieval of dom is definitely not assigned/retrieved directly on the prototype chain. It is probably implemented by some internal methods, so the above string of .hasOwnProperty('innerHTML') are all false.
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
