TypeError: Cannot read properties of undefined (reading 'join')

[ADEV-00]

I am having problem with spotifyApi.areFollowingPlaylist. I am testing the example you provided

  spotifyApi.areFollowingPlaylist('5ieJqeLJjjI8iJWaxeBLuK', [
          'thelinmichael',
          'ella',
        ])
        .then(
          function (data: any) {
            data.body.forEach(function (isFollowing: any) {
              console.log('User is following: ' + isFollowing)
            })
          },
          function (err: any) {
            console.log('Something went wrong!', err)
          }
        ) 

But I am getting the error: TypeError: Cannot read properties of undefined (reading 'join')

[ADEV-00]

For some reason, the function needed a parameter before the playlist id.
I manage to fix my problem like this:

spotifyApi.areFollowingPlaylist('spotify', '5ieJqeLJjjI8iJWaxeBLuK', [
          'thelinmichael',
          'ella',
        ])
        .then(
          function (data: any) {
            data.body.forEach(function (isFollowing: any) {
              console.log('User is following: ' + isFollowing)
            })
          },
          function (err: any) {
            console.log('Something went wrong!', err)
          }
        ) 

Can someone explain to me what this first parameter is?

[kevinguebert]

Looks like the README may need to be updated as the issue may be coming from the followers being undefined

From:

spotify-web-api-node/src/spotify-web-api.js

Lines 1342 to 1348 in be15f1c

	* Check if users are following a playlist.
	* @param {string} userId The playlist's owner's user ID
	* @param {string} playlistId The playlist's ID
	* @param {String[]} User IDs of the following users
	* @param {requestCallback} [callback] Optional callback method to be called instead of the promise.
	* @returns {Promise|undefined} A promise that if successful returns an array of booleans. If rejected,
	* it contains an error object. Not returned if a callback is given.