DEV Community: liu550

Cannot call a child component's function from the parent component. Error: “…is not a function”

liu550 — Fri, 19 Jun 2020 16:25:34 +0000

Hi,

For my website I want to include a feature that helps users randomly click a link programatically. The event happens in the parent component called StreamingPlaza, and its has a list of children components called StreamingCard, each containing a streaming link. The attached screenshots are my code. I got the error "this.roomclicks.current[0].handleClick is not a function." I tried console.log(this.roomclicks.current[0]), and it did print out the StreamingCard child component. I looked through many relevant stackoverflow posts, and the answers suggested that this code was supposed to work. I would appreciate a lot if someone can tell me where I get it wrong. Thanks!

User info not stored in firestore using Redux action object

liu550 — Sun, 26 Apr 2020 01:41:11 +0000

Hi there,

I got a problem with my signUp function, which is a Redux action object called when a user submits a signup form: While a user was successfully created in my firebase authentication page, the user info did not get stored into firestore. I used to place the exact same code for storing user info in firestore in the signup component without using Redux, and it worked fine. I am wondering what might cause the problem. Thanks!

Managing permission to edit user profiles & The downsides of not separating frontend from backend

liu550 — Mon, 20 Apr 2020 19:45:53 +0000

Hi there,

I am using React to build a website and have the following questions:

How can I only allow the owner of a profile to edit it and make it read-only for other users (e.g. LinkedIn profile)?
What are the downsides of directly calling firebase's methods in my frontend to (1) store data into my firebase database and (2) retrieve and display data from the database without using a backend?

Thank you so much for bearing with the beginner questions.

Failing to fetch API

liu550 — Sat, 04 Apr 2020 05:27:01 +0000

Hi there,

I'm trying to fetch a token and session id from the backend when a button is clicked. However, among all the console.log() functions I put in the handleSubmit function, only the first one worked, printing out "ok." I am wondering what caused the program fail to fetch the data from the backend (my backend code does generate a token and session id on localhost:5000/api/sessions). I attached a screenshot of (1) the backend code, (2) the frontend code, (3) proxy.js, and (4) my project folder. I do not include a proxy string or object in package.json. Thanks!

Backend
https://dev-to-uploads.s3.amazonaws.com/i/aeqesx6nal99naoj7gaw.png

Frontend (fetch API)
https://dev-to-uploads.s3.amazonaws.com/i/fgf8as8f0f7qbagu0xjk.png

proxy.js
https://dev-to-uploads.s3.amazonaws.com/i/fxi1h2iowx4bxq7mlaoy.png

src folder
https://dev-to-uploads.s3.amazonaws.com/i/n788uaysq2p8lb77u7tr.png

Problems with Node.js

liu550 — Sat, 21 Mar 2020 19:40:00 +0000

Hi,

I am wondering why my server side code only outputs "Hi ${port}" on console without (1) showing the actual port number or (2) opening up the "locolhost:5000" web page. My command is "npm start server." The screenshots of (1) the code and the (2) scripts part of the package.json file are attached. Thanks!

https://dev-to-uploads.s3.amazonaws.com/i/fqccj2yqjogkszwzkjp5.png

https://dev-to-uploads.s3.amazonaws.com/i/w90w553emwra9deb7y8k.png

Uncaught TypeError: Cannot read property "state" of undefined

liu550 — Tue, 17 Mar 2020 03:04:07 +0000

Hi,

I am wondering why the console reports the error at line 36. Thanks for your help.

Look for advice about a project

liu550 — Thu, 02 Jan 2020 01:00:43 +0000

Hi there,

I am building a web app resembling a combination of Twitch and Zoom: A host can turn on the camera and share his screen, start broadcasting. Other users search on the website for interesting content and then join the room. The reason why I say this app is also like Zoom is that the functionality/purpose of the app is to enable a few people (maybe up to 6 per room) to have remote conversations, and there will be some video-conferencing features added to the app.

Is WebRTC suitable for this application? Also, how are the techniques needed for broadcasting different from the ones needed for multiparty video communication and WebRTC? Thanks. Looking forward to your advice.