const { getAudioDurationInSeconds } = require('get-audio-duration')

getAudioDurationInSeconds('audio.flac').then((duration) => {
  console.log(duration)
})

// If you need to customize the path to ffprobe...

getAudioDurationInSeconds('audio.flac', '/path/to/ffprobe').then((duration) => {
  console.log(duration)
})