CORS Issue while hitting Slack API from Front end App (React)

[Vignesh-raggy]

1. Whether Slack API Methods can be called from Front end Applications like react ?

2. If yes then, We are calling the Slack API from front end web application which is created with react(i.e.. JavaScript framework) and this application is hosted in server now (i.e.. https web app).

We are getting CORS issue while calling any Slack API.

providing Detailed CORS Errors below:

Access to fetch at 'https://slack.com/api/auth.test' from origin 'http://localhost:3000' has been blocked by CORS policy: Request header field traceparent is not allowed by Access-Control-Allow-Headers in preflight response.

Access to fetch at 'https://slack.com/api/conversations.list' from origin 'http://localhost:3000' has been blocked by CORS policy: Request header field traceparent is not allowed by Access-Control-Allow-Headers in preflight response.
The same issue we got in Development environment (https hosted web app).

method 1: We are directly hitting this api https://slack.com/api/conversations.list with needed params.
method 2: And we are trying to use this library also to make api call - https://www.npmjs.com/package/@slack/web-api

in both the methods getting same CORS error.

Kindly Help us on this.

Our requirement : To Share a link from our front end application to any slack channels or DMs.
We planned to use conversations.list api to get all channels and DM list and post the message to particular channel using chat.postmessage API.

[filmaj]

Hello @Vignesh-raggy,

Based on #1505, we will not be adding support for making cross-origin requests to the Slack API in this package. Native browser fetch support for cross-origin API calls requires that the backend API provide specific CORS responses to pre-flight requests, and our backend has no plans to add support for such headers.

However, one workaround you can try is to craft your own 'simple request' and pass your authorization token as a POST body parameter of the request, as per our docs on authentication. See this stackoverflow post on the topic.

[github-actions]

👋 It looks like this issue has been open for 30 days with no activity. We'll mark this as stale for now, and wait 10 days for an update or for further comment before closing this issue out. If you think this issue needs to be prioritized, please comment to get the thread going again! Maintainers also review issues marked as stale on a regular basis and comment or adjust status if the issue needs to be reprioritized.

[github-actions]

As this issue has been inactive for more than one month, we will be closing it. Thank you to all the participants! If you would like to raise a related issue, please create a new issue which includes your specific details and references this issue number.

[NomanQureshi1997]

Whether Slack API Methods can be called from Front end Applications like react ?

No you can not call slack api from frontend due to security concern's.