node.js 中是否需要 json

Question

I would like to include a couple of JSON files in my JavaScript code that are in the same directory as my JavaScript source file.

If I wanted to include another JavaScript file I could simply use require . Now I'm using readFileSync and __dirname to get the JSON, which I think is an ugly way to do it.

Is there something similar for require that enables me to load a JSON file?

Answer 1

As of node v0.5.x yes you can require your JSON just as you would require a js file.

var someObject = require('./somefile.json')

In ES6:

import someObject from ('./somefile.json')

Answer 2

JSON files don't require an explicit exports statement. You don't need to export to use it as Javascript files.

So, you can use just require for valid JSON document.

data.json

{
  "name": "Freddie Mercury"
}

main.js

var obj = require('data.json');

console.log(obj.name); 
//Freddie Mercury

Answer 3

Two of the most common

First way :

let jsonData = require('./JsonFile.json')

let jsonData = require('./JsonFile') // if we omitting .json also works

OR

import jsonData from ('./JsonFile.json')

Second way :

1) synchronously

const fs = require('fs')
let jsonData = JSON.parse(fs.readFileSync('JsonFile.json', 'utf-8'))

2) asynchronously

const fs = require('fs')
let jsonData = {}
fs.readFile('JsonFile.json', 'utf-8', (err, data) => {
  if (err) throw err

  jsonData = JSON.parse(data)
})

Note: 1) if we JsonFile.json is changed, we not get the new data, even if we re run require('./JsonFile.json')

2) The fs.readFile or fs.readFileSync will always re read the file, and get changes

Answer 4

No. Either use readFile or readFileSync (The latter only at startup time).

Or use an existing library like

• cjson

Alternatively write your config in a js file rather then a json file like

module.exports = {
  // json
}

Answer 5

You can import json files by using the node.js v14 experimental json modules flag. More details here

file.js

import data from './folder/file.json'

export default {
  foo () {
    console.log(data)
  }
}

And you call it with node --experimental-json-modules file.js

Answer 6

A nifty non-caching async one liner for node 15 modules:

import { readFile } from 'fs/promises';

const data = await readFile('{{ path }}').then(json => JSON.parse(json)).catch(() => null);

Answer 7

You even can use require of your JSON without specifying the extension .json . It will let you change the file extension to .js without any changes in your imports.

assuming we have ./myJsonFile.json in the same directory.

const data = require('./myJsonFile')

If in the future you'll change ./myJsonFile.json to ./myJsonFile.js nothing should be changed in the import.

Answer 8

You can use a module to create a require.

import { createRequire } from 'module'
const require = createRequire(import.meta.url)
const foo = require('./foo.js')

Answer 9

如果你使用的是 typescript ，你可以在你的 tsconfig.json 中添加一个名为resolveJsonModule: true的新字段，然后你可以像这样导入任何 .json 文件的所有信息：

import * as jsonfile from "./path/to/json"