node-study

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Intro of node

Install&& Use

Use nvm to manage the node version

Use node index.js to run single script

Node file system

Use fs.writeFile(file,data) to write to a file and fs.readFile()` to read from a file. need to require fs first.

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const fs = require('fs');

const data = 'This is a test message\n';

// write data into test.txt without deleting the existing data
fs.writeFile('test.txt', data, { flag: 'a+' }, (err) => {
    if (err) {
        console.log(err);
        return;
    }
    console.log('Successfully write data into test.txt');
});

// read data from test.txt
fs.readFile('test.txt', 'utf8', (err, data) => {
    if (err) {
        console.log(err);
        return;
    }
    console.log(data);
});

NPM

use npm init to init a npm project

When using the functions in the package normally it needs to use var xxx = require("xxxxx"). But using ECMAScript Modules we can use import xxx from "xxxxx". You need to add "type": "module", in package.json file in order to use import.