I have this error when I compile my code in node.js, how can I fix it?
RefernceError: fetch is not defined
This is the function I am doing, it is responsible for recovering information from a specific movie database.
function getMovieTitles(substr){ pageNumber=1; let url = ' + substr + "&page=" + pageNumber; fetch(url).then((resp) => resp.json()).then(function(data) { let movies = data.data; let totPages = data.total_pages; let sortArray = []; for(let i=0; i<movies.length;i++){ sortArray.push(data.data[i].Title); } for(let i=2; i<=totPages; i++){ let newPage = i; let url1 = ' + substr + "&page=" + newPage; fetch(url1).then(function(response) { var contentType = response.headers.get("content-type"); if(contentType && contentType.indexOf("application/json") !== -1) { return response.json().then(function(json) { //console.log(json); //uncomment this console.log to see the JSON data. for(let i=0; i<json.data.length;i++){ sortArray.push(json.data[i].Title); } if(i==totPages)console.log(sortArray.sort()); }); } else { console.log("Oops, we haven't got JSON!"); } }); } }) .catch(function(error) { console.log(error); });
}23 Answers
The fetch API is not implemented in Node.
You need to use an external module for that, like node-fetch.
Install it in your Node application like this
npm install node-fetchthen put the line below at the top of the files where you are using the fetch API:
import fetch from "node-fetch";This is a quick dirty fix, please try to eliminate this usage in production code.
If fetch has to be accessible with a global scope
import fetch from 'node-fetch'
globalThis.fetch = fetchYou can use cross-fetch from @lquixada
Platform agnostic: browsers, node or react native
Install
npm install --save cross-fetchUsage
With promises:
import fetch from 'cross-fetch';
// Or just: import 'cross-fetch/polyfill';
fetch('//) .then(res => { if (res.status >= 400) { throw new Error("Bad response from server"); } return res.json(); }) .then(user => { console.log(user); }) .catch(err => { console.error(err); });With async/await:
import fetch from 'cross-fetch';
// Or just: import 'cross-fetch/polyfill';
(async () => { try { const res = await fetch('//); if (res.status >= 400) { throw new Error("Bad response from server"); } const user = await res.json(); console.log(user); } catch (err) { console.error(err); }
})();If you want to avoid npm install and not running in browser, you can also use nodejs https module;
const https = require('https')
const url = "";
https.get(url, res => { let data = ''; res.on('data', chunk => { data += chunk; }); res.on('end', () => { data = JSON.parse(data); console.log(data); })
}).on('error', err => { console.log(err.message);
})You should add this import in your file:
import * as fetch from 'node-fetch';And then, run this code to add the node-fetch:$ yarn add node-fetch
If you're working with typescript, then install node-fetch types:$ yarn add @types/node-fetch
Node.js hasn't implemented the fetch() method, but you can use one of the external modules of this fantastic execution environment for JavaScript.
In one of the other answers, "node-fetch" is cited and that's a good choice.
In your project folder (the directory where you have the .js scripts) install that module with the command:
npm i node-fetch --saveThen use it as a constant in the script you want to execute with Node.js, something like this:
const fetch = require("node-fetch");You have to use the isomorphic-fetch module to your Node project because Node does not contain Fetch API yet. For fixing this problem run below command:
npm install --save isomorphic-fetch es6-promiseAfter installation use below code in your project:
import "isomorphic-fetch"EDITED - New Solution
To use the latest version (3.0.0) you must do the import like this:
const fetch = (url) => import('node-fetch').then(({default: fetch}) => fetch(url));Old Anwser:
This may not be the best solution, but if you install this version :
npm install node-fetch@1.7.3you can now use the line below without error's.
const fetch = require("node-fetch");Best one is Axios library for fetching.
use npm i --save axios for installng and use it like fetch, just write axios instead of fetch and then get response in then().
For those also using typescript on node-js and are getting a ReferenceError: fetch is not defined error
npm install these packages:
"amazon-cognito-identity-js": "3.0.11" "node-fetch": "^2.3.0"Then include:
import Global = NodeJS.Global;
export interface GlobalWithCognitoFix extends Global { fetch: any
}
declare const global: GlobalWithCognitoFix;
global.fetch = require('node-fetch');fetch came to Node v17 under experimental flag --experimental-fetch
It will be available in Node v18 without the flag.
You no longer need any additional package to be installed
1It seems fetch support URL scheme with "http" or "https" for CORS request.
Install node fetch library npm install node-fetch, read the file and parse to json.
const fs = require('fs')
const readJson = filename => { return new Promise((resolve, reject) => { if (filename.toLowerCase().endsWith(".json")) { fs.readFile(filename, (err, data) => { if (err) { reject(err) return } resolve(JSON.parse(data)) }) } else { reject(new Error("Invalid filetype, <*.json> required.")) return } })
}
// usage
const filename = "../data.json"
readJson(filename).then(data => console.log(data)).catch(err => console.log(err.message))In node.js you can use : node-fetch package
npm i node-fetchthen :
import fetch from 'node-fetch';here is a full sample in (nodejs) :
import fetch from "node-fetch";
const fetchData = async () => { const res = await fetch(""); // fetch() returns a promise, so we need to wait for it const country = await res.json(); // res is now only an HTTP response, so we need to call res.json() console.log(country); // Columbia's data will be logged to the dev console
};
fetchData();In HackerRank, some libraries are installed by default and some are not.
Because it is running Node.js, the fetch API is not installed by default.
The best thing for you to do is to check whether the libraries are or not installed.
on the top of the exercise, there is the following:
const https = require('https');Please try to add this to the top as well:
const axios = require('axios');and then run the code.
If there is a compilation error, then it's not available, otherwise you can use axios, which is a good alternative to fetch
To use it with then, you can:
function getMovieTitles(substr){ axios.get(url) .then(function(response){ console.log(response.data); })
}or taking advantage of the async/await
async function getMovieTitles(substr){ let response = await axios.get(url) console.log(response.data);
}This is the related github issueThis bug is related to the 2.0.0 version, you can solve it by simply upgrading to version 2.1.0.
You can runnpm i graphql-request@2.1.0-next.1
The following works for me in Node.js 12.x:
npm i node-fetch;to initialize the Dropbox instance:
var Dropbox = require("dropbox").Dropbox;
var dbx = new Dropbox({ accessToken: <your access token>, fetch: require("node-fetch")
});to e.g. upload a content (an asynchronous method used in this case):
await dbx.filesUpload({ contents: <your content>, path: <file path>
});For me these are looking more simple.
npm install node-fetchimport fetch from "node-fetch";There are actually a lot of different libraries for making fetch available in the browser.
The main ones I'm aware of are:
I currently use node-fetch, and it has worked fine, but I don't really know which one is "the best". (though the openbase.com pages I linked to provide some metadata on usage [eg. Github stars, npm downloads], which can help)
This answer does not directly answer this question. Instead it suggests for an alternative.
Why? Because the using 'node-fetch' is getting complicated since you cannot import the updated versions using const fetch = require('node-fetch') . You will have to do more things to just make it work.
Try using axios package:
- Simple installation
npm i axios - code for fetching goes like
const response = await axios.get(url).then(res => res.data)This worked for me:
const nodeFetch = require('node-fetch') as typeof fetch;Just make your app.js file Extension as app.mjs and the problem will be solved!!!:)
Might sound silly but I simply called npm i node-fetch --save in the wrong project. Make sure you are in the correct directory.
If need install:
npm install --save global-fetchthen
var fetch = require("node-fetch");
