Develop Reference

Unsubscribe email using Fetch api Javascript

I have a form where i enter an email and it gets ''subscribed'' in a user.json file using a fetch api on node server.My task is to :
upon clicking on the "Unsubscribe" button, implement the functionality for unsubscribing from the community list. For that, make POST Ajax request using http://localhost:3000/unsubscribe endpoint.
I tried to make the function but it wasnt succeseful so i deleted it. Also,i need to do the following :
While the requests to http://localhost:3000/subscribe and
http://localhost:3000/unsubscribe endpoints are in progress, prevent
additional requests upon clicking on "Subscribe" and "Unsubscribe".
Also, disable them (use the disabled attribute) and style them using
opacity: 0.5.
For me ajax requests,fetch and javascript is something new,so i dont know really well how to do this task,if you could help me i'll be happy,thanks in advance.
fetch code for subscribing:
import { validateEmail } from './email-validator.js'
export const sendSubscribe = (emailInput) => {
const isValidEmail = validateEmail(emailInput)
if (isValidEmail === true) {
sendData(emailInput);
}
}
export const sendHttpRequest = (method, url, data) => {
return fetch(url, {
method: method,
body: JSON.stringify(data),
headers: data ? {
'Content-Type': 'application/json'
} : {}
}).then(response => {
if (response.status >= 400) {
return response.json().then(errResData => {
const error = new Error('Something went wrong!');
error.data = errResData;
throw error;
});
}
return response.json();
});
};
const sendData = (emailInput) => {
sendHttpRequest('POST', 'http://localhost:8080/subscribe', {
email: emailInput
}).then(responseData => {
return responseData
}).catch(err => {
console.log(err, err.data);
window.alert(err.data.error)
});
}
index.js from route node server:
const express = require('express');
const router = express.Router();
const FileStorage = require('../services/FileStorage');
/* POST /subscribe */
router.post('/subscribe', async function (req, res) {
try {
if (!req.body || !req.body.email) {
return res.status(400).json({ error: "Wrong payload" });
}
if (req.body.email === 'forbidden#gmail.com') {
return res.status(422).json({ error: "Email is already in use" });
}
const data = {email: req.body.email};
await FileStorage.writeFile('user.json', data);
await res.json({success: true})
} catch (e) {
console.log(e);
res.status(500).send('Internal error');
}
});
/* GET /unsubscribe */
router.post('/unsubscribe ', async function (req, res) {
try {
await FileStorage.deleteFile('user.json');
await FileStorage.writeFile('user-analytics.json', []);
await FileStorage.writeFile('performance-analytics.json', []);
await res.json({success: true})
} catch (e) {
console.log(e);
res.status(500).send('Internal error');
}
});
module.exports = router;
And user.json file looks like this :
{"email":"Email#gmail.com"}
This is my attempt for unsubscribing :
export const unsubscribeUser = () => {
try {
const response = fetch('http://localhost:8080/unsubscribe', {
method: "POST"
});
if (!response.ok) {
const message = 'Error with Status Code: ' + response.status;
throw new Error(message);
}
const data = response.json();
console.log(data);
} catch (error) {
console.log('Error: ' + error);
}
}
It gives the following errors:
Error: Error: Error with Status Code: undefined
main.js:2
main.js:2 POST http://localhost:8080/unsubscribe 404 (Not Found)
FileStorage.js:
const fs = require('fs');
const fsp = fs.promises;
class FileStorage {
static getRealPath(path) {
return `${global.appRoot}/storage/${path}`
}
static async checkFileExist(path, mode = fs.constants.F_OK) {
try {
await fsp.access(FileStorage.getRealPath(path), mode);
return true
} catch (e) {
return false
}
}
static async readFile(path) {
if (await FileStorage.checkFileExist(path)) {
return await fsp.readFile(FileStorage.getRealPath(path), 'utf-8');
} else {
throw new Error('File read error');
}
}
static async readJsonFile(path) {
const rawJson = await FileStorage.readFile(path);
try {
return JSON.parse(rawJson);
} catch (e) {
return {error: 'Non valid JSON in file content'};
}
}
static async writeFile(path, content) {
const preparedContent = typeof content !== 'string' && typeof content === 'object' ? JSON.stringify(content) : content;
return await fsp.writeFile(FileStorage.getRealPath(path), preparedContent);
}
static async deleteFile(path) {
if (!await FileStorage.checkFileExist(path, fs.constants.F_OK | fs.constants.W_OK)) {
return await fsp.unlink(FileStorage.getRealPath(path));
}
return true;
}
}
module.exports = FileStorage;

You should consider using a database for handling CRUD operations on your persisted data. If you must use filestorage, theres a flat file DB library called lowdb that can make working the files easier.
As for preventing duplicate requests, you can track if user has already made a request.
let fetchBtn = document.getElementById('fetch')
let isFetching = false
fetchBtn.addEventListener('click', handleClick)
async function handleClick(){
if (isFetching) return // do nothing if request already made
isFetching = true
disableBtn()
const response = await fetchMock()
isFetching = false
enableBtn()
}
function fetchMock(){
// const response = await fetch("https://example.com");
return new Promise(resolve => setTimeout (() => resolve('hello'), 2000))
}
function disableBtn(){
fetchBtn.setAttribute('disabled', 'disabled');
fetchBtn.style.opacity = "0.5"
}
function enableBtn(){
fetchBtn.removeAttribute('disabled');
fetchBtn.style.opacity = "1"
}
<button type="button" id="fetch">Fetch</button>

error retrieving user Id token assigned by firebase in the client side

I am using JWT based authentication using firebase Admin SDK in express js.
according to the sign in with custom token when we sign the user with the function signInWithCustomToken(token) firebase sets a user-id token for that user.
according to retrieve id tokens
firebase.auth().currentUser.getIdToken(/* forceRefresh */ true).then(function(idToken) {
// Send token to your backend via HTTPS
// ...
}).catch(function(error) {
// Handle error
});
we can get the token if the user is logged in
but executing this I get error that getIdToken value is null.
i changed the code to
const getUser = async () => {
const token = await firebase.auth().currentUser.getIdToken(/* forceRefresh */true).catch(function(error) {
console.log(error)
});
const userToken = await token;
const getData = async (userToken) => {
const response = await fetch('/getUser', {
method: 'POST',
headers: {
'Accept': 'application/json',
'Content-Type': 'application/json'
},
body: JSON.stringify({idToken: userToke})
})
const data = await response.json()
console.log(responnse)
}
}
getUser();
but still receiving the same error
I looked up for some solutions and found similar answers to the question one of which I implemented was solution
it used onAuthStateChanged method and I am using
<script src="https://www.gstatic.com/firebasejs/7.14.1/firebase-app.js"></script>
<script src="https://www.gstatic.com/firebasejs/7.14.1/firebase-auth.js"></script>
in cdn but now am getting
Uncaught (in promise) TypeError: firebase.auth.onAuthStateChanged is not a function
at profile:40
at new Promise (<anonymous>)
at getIdTokenRefreshed (profile:37)
at profile:50
I changed the above code to this
firebase.initializeApp(firebaseConfig);
const getIdTokenRefreshed = async () => {
return new Promise(async (resolve, reject) => {
const unsubscribe = await firebase
.auth
.onAuthStateChanged(async user => {
unsubscribe()
const refreshedToken = await user
.getIdToken(true)
.catch(err => console.error(err))
resolve(refreshedToken)
console.log(refreshedToken)
}, reject)
});
}
getIdTokenRefreshed();
still getting the second error where onAuthStateChanged is not defined
how do I retrieve the user id token?
UPDATE
const getIdTokenRefreshed = async () => {
try {
const user = firebase.auth().currentUser
if (user) {
const token = await user.getIdToken(true)
console.log(`Token: ${token}`)
return token
} else {
console.log("No user is logged in")
}
} catch (e) {
console.log(`Something went wrong: ${e}`)
}
}
after implementing the above code this is the error
await is only valid in async functions and the top level bodies of modules

First, I'd recommend updating Firebase SDK to latest version which is 8.9.1 at the time of writing this.
<script src="https://www.gstatic.com/firebasejs/8.9.1/firebase-app.js"></script>
<script src="https://www.gstatic.com/firebasejs/8.9.1/firebase-auth.js"></script>
If you take a look at onAuthStateChanged part in the documentation, it should be:
firebase.auth().onAuthStateChanged(...)
// ^^
// not firebase.auth.onAuthStateChanged
The onAuthStateChanged won't be triggered unless you call the getIdTokenRefreshed function. You can simply refactor that function to:
const getIdTokenRefreshed = async () => {
try {
const user = firebase.auth().currentUser
if (user) {
const token = await user.getIdToken(true)
console.log(`Token: ${token}`)
return token
} else {
console.log("No user is logged in")
}
} catch (e) {
console.log(`Something went wrong: ${e}`)
}
}
Lastly, the variable name is userToken but in request body it is body: JSON.stringify({idToken: userToke}) and you don't need an await before a variable name. Try refactoring the getUser function to:
//const token = await firebase.auth().currentUser.getIdToken(/* forceRefresh */true).catch(function(error) {
// console.log(error)
//});
//const userToken = await token;
const getUser = async () => {
const token = await firebase.auth().currentUser.getIdToken(true)
const response = await fetch('/getUser', {
method: 'POST',
headers: {
'Accept': 'application/json',
'Content-Type': 'application/json'
},
body: JSON.stringify({idToken: token})
})
const data = await response.json()
console.log(data)
return data
}
getUser().then(data => {
console.log("Data received")
})

Handling query in React and Express

Somewhere in my React application I used REST API to send request to the server. In my URL I want to use query (in the postIconsTransition method), but when I send a request to the server, server tells me could not found this URL (I build this error in my server). If I use this URL without any query the request in the postIconsTransition method works fine. postId and authContext.userId work fine, can anyone tell me what's wrong with my code?
In my component where I send request:
const likeHandler = async () => {
setLike(prevState => !prevState);
if (!like) {
try {
await postIconsTransition(props.postId, "inc");
} catch (error) {}
} else {
try {
await postIconsTransition(props.postId, "dec");
} catch (error) {}
}
};
In useHttp.js component:
const postIconsTransition = async (postId, addtionAddress) => {
return await transitionData(
`http://localhost:5000/post/${postId}/${authContext.userId}?t=${addtionAddress}`,
"POST",
null,
{ Authorization: `Bearer ${authContext.token}` }
);
};
transitionData method:
const transitionData = useCallback(
async (url, method = "GET", body = null, headers = {}) => {
setIsLoading(true);
const abortController = new AbortController();
activeHttpRequest.current.push(abortController);
try {
const response = await fetch(url, {
method,
body,
headers,
signal: abortController.signal
});
const responseData = await response.json();
activeHttpRequest.current = activeHttpRequest.current.filter(
reqCtrl => reqCtrl !== abortController
);
if (!response.ok) {
throw new Error(responseData.message);
}
setIsLoading(false);
return responseData;
} catch (error) {
modalContext.err(error);
setIsLoading(false);
throw error;
}
},
[modalContext.err]
);
In Express:
router.post(
"/:postId/:userId?t=inc",
tokenChecker,
postController.updateLikesComments
);
router.post(
"/:postId/:userId?t=dec",
tokenChecker,
postController.updateLikesComments
);
All of them work fine but when I use query in my URL, it's not working any more.

You don't specify query parameters in express routes like that. Just send them. Express can read it.
router.post(
"/:postId/:userId",
tokenChecker,
postController.updateLikesComments
);
// Notice that you don't need the other one.
and in your controller check the parameter
// controller's code
const t = req.query.t;
if (t === 'inc') {
// do what you want here
}
if (t === 'dec') {
// do what you want here
}

Service call is not going in react-native. Getting warning like "Possible unhandled Promise Rejection, Reference error: response is not defined"

I am new to react native and making service call for the first time. My problem is service call is not going and getting warning like
Possible unhandled Promise Rejection, Reference error: response is not defined.
I am trying to hit loginUser function.
Api.js
const BASE_URL = "http://localhost:8200";
export const api = async (url, method, body = null, headers = {}) => {
try {
const endPoint = BASE_URL.concat(url);
const reqBody = body ? JSON.stringify(body) : null;
const fetchParams = {method, headers};
if((method === "POST" || method === "PUT") && !reqBody) {
throw new Error("Request body required");
}
if(reqBody) {
console.log("ReQBody--->"+reqBody);
fetchParams.headers["Content-type"] = "application/json";
fetchParams.body = reqBody;
}
const fetchPromise = await fetch(endPoint, fetchParams);
const timeOutPromise = new Promise((resolve, reject) => {
setTimeout(() => {
reject("Request Timeout");
}, 3000);
});
const response = await Promise.race([fetchPromise, timeOutPromise]);
return response;
} catch (e) {
return e;
}
}
export const fetchApi = async (url, method, body, statusCode, token = null, loader = false) => {
console.log("In FetchAPi Function");
try {
const headers = {}
const result = {
token: null,
success: false,
responseBody: null
};
if(token) {
headers["securityKey"] = token;
}
const response = await api(url, method, body, headers);
console.log("fetchApi-->>"+response);
if(response.status === statusCode) {
result.success = true;
let responseBody;
const responseText = await response.text();
try {
responseBody = JSON.parse(responseText);
} catch (e) {
responseBody = responseText;
}
result.responseBody = responseBody;
return result;
}
let errorBody;
const errorText = await response.text();
try {
errorBody = JSON.parse(errorText);
} catch (e) {
errorBody = errorText;
}
result.responseBody = errorBody;
console.log("FetchApi(Result)--->>"+result);
throw result;
} catch (error) {
return error;
}
}
auth.actions.js
export const loginUser = (payload) => {
console.log("In LoginUser function2");
return async (dispatch) => {
<-----**I am not able to enter into this block**------>
try {
dispatch({
type: "LOGIN_USER_LOADING"
});
console.log("In LoginUser function3");
const response = await fetchApi("/login", "POST", payload, 200);
if(response.success) {
dispatch({
type: "LOGIN_USER_SUCCESS",
});
dispatch({
type: "AUTH_USER_SUCCESS",
token: response.token
});
dispatch({
type: "GET_USER_SUCCESS",
payload: response.responseBody
});
return response;
} else {
throw response;
}
} catch (error) {
dispatch({
type: "LOGIN_USER_FAIL",
payload: error.responseBody
});
return error;
}
}
}
In console log, I can't see anything in network tab. In the android emulator, the mentioned warning has come.
My console tab

I see that your BASE_URL is served using an http endpoint. You can only make requests to https endpoints from react native projects. A possible workaround is to use ngrok. Just download it and run ./ngrok http 8200 since your port number is 8200. It will expose an HTTPS endpoint and replace your BASE_URL with that link and try fetching the data again.

I use the following code to make API calls. See if you can integrate it in your code. it is quite simple:
In a class called FetchService:
class FetchService {
adminAuth(cb, data) {
console.log('here in the fetch service');
return fetch(
baseURL + "login",
{
method: "POST",
headers: {
Accept: "application/json",
},
body: data
}
)
.then((response) => response.json())
.then(responsej => {
cb(null, responsej);
})
.catch(error => {
cb(error, null);
});
}
}
export default FetchService;
Then call it from your component using:
import FetchService from './FetchService';
const fetcher = new FetchService;
export default class LoginScreen extends React.Component {
fetchData() {
const data = new FormData();
data.append('username',this.state.username);
data.append('password',this.state.password);
fetcher.wastereport((err, responsej) => {
if(err) {
//handle error here
} else {
//handle response here
}
}, data);
}
}

Async function returning undefined instead of data

I'm doing requests to my API server to authenticate a user, that's not the problem. The problem is that I don't know why my async function doesn't return anything, and I get an error because the data that I want from this function is undefined.
Don't worry if the error management is ugly and in general I can do this better, I'll do that after fixing this problem.
Utils.js class
async Auth(username, password) {
const body = {
username: username,
password: password
};
let req_uuid = '';
await this.setupUUID()
.then((uuid) => {
req_uuid = uuid;
})
.catch((e) => {
console.error(e);
});
let jwtData = {
"req_uuid": req_uuid,
"origin": "launcher",
"scope": "ec_auth"
};
console.log(req_uuid);
let jwtToken = jwt.sign(jwtData, 'lulz');
await fetch('http://api.myapi.cc/authenticate', {
method: 'POST',
headers: { "Content-Type": "application/json", "identify": jwtToken },
body: JSON.stringify(body),
})
.then((res) => {
// console.log(res);
// If the status is OK (200) get the json data of the response containing the token and return it
if (res.status == 200) {
res.json()
.then((data) => {
return Promise.resolve(data);
});
// If the response status is 401 return an error containing the error code and message
} else if (res.status == 401) {
res.json()
.then((data) => {
console.log(data.message);
});
throw ({ code: 401, msg: 'Wrong username or password' });
// If the response status is 400 (Bad Request) display unknown error message (this sould never happen)
} else if (res.status == 400) {
throw ({ code: 400, msg: 'Unknown error, contact support for help. \nError code: 400' });
}
})
// If there's an error with the fetch request itself then display a dialog box with the error message
.catch((error) => {
// If it's a "normal" error, so it has a code, don't put inside a new error object
if(error.code) {
return Promise.reject(error);
} else {
return Promise.reject({ code: 'critical', msg: error });
}
});
}
Main.js file
utils.Auth('user123', 'admin')
.then((res) => {
console.log(res); // undefined
});

Your Async function must return the last promise:
return fetch('http://api.myapi.cc/authenticate', ...);
or await the result and return it:
var x = await fetch('http://api.myapi.cc/authenticate', ...);
// do something with x and...
return x;
Notice that you don’t need to mix promise syntax (.then) with await. You can, but you don’t need to, and probably shouldn’t.
These two functions do exactly the same thing:
function a() {
return functionReturningPromise().then(function (result) {
return result + 1;
});
}
async function b() {
return (await functionReturningPromise()) + 1;
}

await is not to be used with then.
let data = await this.setupUUID();
or
let data=null;
setupUUID().then(res=> data = res)

I would try something like this:
const postReq = async (jwtToken) => {
const body = {
username: username,
password: password,
};
try {
const res = await fetch('http://api.myapi.cc/authenticate', {
method: 'POST',
headers: { "Content-Type": "application/json", "identify": jwtToken },
body: JSON.stringify(body),
})
if (res) {
if (res.status == 200) {
return res.json();
} else if (res.status == 401) {
const data = res.json();
console.log(data.message)
throw ({ code: 401, msg: 'Wrong username or password' });
} else if (res.status == 400) {
throw ({ code: 400, msg: 'Unknown error, contact support for help. \nError code: 400' });
}
}
} catch (err) {
console.error(err)
}
};
const Auth = async (username, password) => {
const jwtData = {
"origin": "launcher",
"scope": "ec_auth"
};
try {
const req_uuid = await this.setupUUID();
if (req_uuid) {
jwtData["req_uuid"] = req_uuid;
const jwtToken = jwt.sign(jwtData, 'lulz');
return await postReq(jwtToken);
}
} catch (err) {
console.error(err);
};
}