Node.js document is not defined

Why node.js does not recognize document.GetElementById? It says 'ReferenceError: docu开发者_StackOverflow中文版ment is not defined'. What can I do?

ReferenceError: document is not defined
at Object.<anonymous> (C:\Users\Desktop\main.js:9:18)
at Module._compile (module.js:460:26)
at Object.Module._extensions..js (module.js:478:10)
at Module.load (module.js:355:32)
at Function.Module._load (module.js:310:12)
at Function.Module.runMain (module.js:501:10)
at startup (node.js:129:16)
at node.js:814:3

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document relates to the DOM (Document Object Model) in a web browser.

Node.js, however, is not a browser environment. It is a server environment, much like PHP or Perl, and as such, you can’t access the browser’s DOM or do anything specific to browser-hosted JavaScript.

The closest you could get is using something like browserify to include Node.js modules in your client-side code.

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You could use JSDom to add Dom support to Node. To make a variable global you can use either

GLOBAL.document = new JSDOM(html).window.document;

or

global.document = new JSDOM(html).window.document;

where html is your website as a string.

To use JSDom include it in your project with:

const jsdom = require("jsdom");
const { JSDOM } = jsdom;

or in plain js with:

var jsdom = require("jsdom");
var JSDOM = jsdom.JSDOM;

I hope this is answering your question.

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To understand the answer, it's necessary to know the relationship of: Javascript Engine, Browser and Node.js.

Javascript Engine: is Javascript compiler which turns JS into machine code. For example, V8, is a great one. Technically V8 is developed in C++ (you can regard it as a C++ program).

V8 implements ECMAScript, which is a standard of Javascript language defining the features and functionalities of JavaScript.

But DOM operation is not defined by ECMAScript. So V8 doesn't support it.

Browser: And developers can use document for DOM operation in browser, because DOM operation is provided by browser, for example: Chrome.

Chrome is also developed by C++ and V8(as mentioned abvoe, which is developed by C++ as well) is embedded into Chrome to interpret Javascript. So Chrome expends or adds features to Javascript by binding JS command and C++ implementation together.

Nodejs: different from the Chrome, it is a server side program. But the same thing is that Nodejs is developed by C++ and V8 is embedded into Nodejs to handle js. Nodejs expands features of Javascript in the similar way with Chrome. But since server side doesn't need to handle DOM, so you can not access such functions inside Nodejs.

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From the docs just add this comment to the top of your .test.js file to configure your environment:

/**
* @jest-environment jsdom
*/

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If you are in React make sure u properly use JSX elements and render without document element. If you need to use document then use

if (typeof window !== 'undefined') { here u can use document. element }

but u cannot use it to render inside because in React conditional render doesn't work

u can use instead:

import Register from './Register'
import { Box, Center } from '@chakra-ui/react'
function App() {
    return (
        <main>
            <Box>
                <Register />
            </Box>
        </main>
    )
}

export default App

where Register is example of element you want to render

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OK, shorter answer is you wanna access document Object which is only available in the window and front end side, don't forget that document === window.document which you don't have access in the server and node side...

So never try something like this on your node side for example getting root element by ID which will throw the error, instead try to access it from FrontEnd:

document.getElementById('root');

will throw an Error:

ReferenceError: document is not defined
at Object.<anonymous> (C:\Users\Desktop\app.js:12:50)
at Module._compile (my.js:490:34)
at Object.Module._extensions..js (my.js:518:10)
at Module.load (my.js:555:42)
at Function.Module._load (my.js:610:12)
at Function.Module.runMain (my.js:701:10)
at startup (node.js:899:16)
at node.js:901:3

The short answer is don't use document and window object in node.js as they are not available in node.js...

Using Domino could help in some cases for accessing the dom...

As the name might suggest, domino's goal is to provide a DOM in Node.

In contrast to the original dom.js project, domino was not designed to run untrusted code. Hence it doesn't have to hide its internals behind a proxy facade which makes the code not only simpler, but also more performant.

Domino currently doesn't use any harmony features like proxies or WeakMaps and therefore also runs in older Node versions.

For more info, visit here...

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• "npm install npm -g"
• after that "npm install -g typescript"

this command helped me for this problem