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https://github.com/arthurgousset/nodejs
✨ node.js cheat sheet
https://github.com/arthurgousset/nodejs
Last synced: 18 days ago
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✨ node.js cheat sheet
- Host: GitHub
- URL: https://github.com/arthurgousset/nodejs
- Owner: arthurgousset
- Created: 2024-05-01T12:25:01.000Z (7 months ago)
- Default Branch: main
- Last Pushed: 2024-05-07T10:56:17.000Z (6 months ago)
- Last Synced: 2024-10-14T01:16:58.940Z (about 1 month ago)
- Homepage:
- Size: 1.95 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# Node.js (Cheat Sheet)
## REPL
> A read--eval--print loop (REPL) or language shell, is a simple interactive programming environment
> that takes single user inputs, executes them, and returns the result to the user; a program
> written in a REPL environment is executed piecewise.
Source:
[wikipedia > Read–eval–print loop](https://en.wikipedia.org/wiki/Read%E2%80%93eval%E2%80%93print_loop)
Simply open your terminal and type `node` to start the REPL.
```sh
$ node
Welcome to Node.js v18.14.2.
Type ".help" for more information.
>
```
### Import modules
Source: ChatGPT
Node.js supports dynamic imports using the `import()` function, which returns a promise. This method
is suitable for the REPL as it can handle asynchronous module loading. You can use it like so:
```sh
> const { BigNumber } = await import('bignumber.js');
```
This line tells Node.js to asynchronously load `bignumber.js` and extract `BigNumber` from the
exported values. The `await` keyword is used because `import()` returns a promise, and we need to
wait for the promise to resolve before continuing.
You can alsop import specific functions from a module using dynamic imports. Here's how to import
`readFileSync`:
```sh
> const { readFileSync } = await import('fs');
```
This line of code uses the ES module dynamic import syntax to load the `fs` module and destructures
`readFileSync` from it. This approach is compatible with the Node.js REPL and provides an
asynchronous way to load modules.
For example:
```sh
$ node
Welcome to Node.js v18.14.2.
Type ".help" for more information.
> const transactions = [
... {
... contract: 'GoldToken',
... function: 'transfer',
... args: ['0xC870dc32e84531DA06C0156f0dfa73CfA091C4bd', '42'],
... value: '0',
... },
... ]
> const transactionsToBeSaved = JSON.stringify(transactions)
undefined
> fs.writeFileSync('transactions.json', transactionsToBeSaved, { flag: 'w' })
undefined
> const { readFileSync } = await import('fs');
undefined
> const jsonString = readFileSync('transactions.json').toString()
undefined
> jsonString
'[{"contract":"GoldToken","function":"transfer","args":["0xC870dc32e84531DA06C0156f0dfa73CfA091C4bd","42"],"value":"0"}]'
> const path = await import('path');
undefined
> const currentDir = process.cwd();
undefined
> const filePath = path.join(currentDir, 'transactions.json');
undefined
> filePath
'/Users/arthur/Documents/celo-org/developer-tooling/transactions.json'
```