Only works in an instagram post page. Takes the text you have in the comment input and post each line as a comment every 2s

ig.js

const frm = document.querySelector('article form')
const commentBox = frm.querySelector('textarea')
const postButton = frm.querySelector('button')

const comments = commentBox.value.split('\n').filter(c => c.length)

const postComment = comment => {
  console.log('Commenting: ', comment)
  let lastValue = commentBox.value
  commentBox.value = comment
  let event = new Event('input', { bubbles: true })
  let tracker = commentBox._valueTracker
  if (tracker)
    tracker.setValue(lastValue)
  }
  commentBox.dispatchEvent(event)
  postButton.click()
}

comments.forEach((comment, i) => {
  setTimeout(() => postComment(comment) , i * 2000)
})