Uncaught TypeError: Cannot read properties of undefined (reading 'replace')

Question

I am presenting this error when uploading the player to the server since locally it works fine.

Let me explain a bit, the player locally shows the song that is playing, the one that is coming and the one that has already played, but when uploading to the server I get the following error: Uncaught TypeError: Cannot read properties of undefined (reading 'replace' ) in the following lines of code but I don't exactly understand why. I would like to know if you can guide me on this to finish this project and deliver it, thanks in advance.

 let song = data.currentSong.replace(/'/g, '\'');
    currentSong = song.replace(/&/g, '&');

    let artist = data.currentArtist.replace(/'/g, '\'');
    currentArtist = artist.replace(/&/g, '&');

Answer 1

I had the same error and I fixed it like this:

Before:

 localizeDate(date) {
   date = date.replace("T", "/");
   return date.replace(".000000Z", "");
 },

After:

localizeDate(date) {
  if(!date) return
  date = date.replace("T", "/");
  return date.replace(".000000Z", "");
},

The issue is that the function is called before any data loads from the server.

You could also fix it with Promises, async/wait or loaders.