Custom JS, add a button to copy username in Line 1-on-1 chat

line-copy-username.js

function getName() {
  return getNameElement().textContent
}

function getNameElement() {
  return document.querySelector('#_chat_header_area h1')
}

function copyText(text) {
  const inputId = 'copy-input'
  let input = document.getElementById(inputId)
  console.log(`> input: `, input)

  if (!input) {
    const inputEl = document.createElement('input')
    inputEl.id = inputId
    inputEl.type = 'text'
    document.body.appendChild(inputEl)
    input = inputEl
  }

  input.value = text
  input.select()
  document.execCommand('copy')
  input.remove()
  alert('Copied')
}

function handleClickCopyButton() {
  const name = getName()
  console.log(`name: ${name}`)
  copyText(name)
}

function addCopyButton() {
  const buttonId = 'custom-copy-button'

  try {
    document.getElementById(buttonId).remove()
  } catch(err) {
    //
  }

  const button = document.createElement('button')
  button.textContent = `Copy username`
  button.id = buttonId
  button.style.cssText = `
    position: fixed;
    top: 54px;
    right: 15px;
    background-color: #f37A01;
    padding: 10px;
    color: white;
    border-radius: 3px;
    z-index: 100;
  `

  button.addEventListener('click', handleClickCopyButton)

  document.body.appendChild(button)
  return button
}

addCopyButton()