addMembers.js

names = [
'user a',
'user b',
'user c',
]

for (let i = 0; i < names.length; i++) {
  Array.from(document.querySelectorAll('button')).filter(b => b.innerText == 'Add member')[0].click()
}

inputBoxList = Array.from(document.querySelectorAll('ul')).slice(-1)[0]
inputBoxes = inputBoxList.querySelectorAll('input')


for (let i = 0; i < names.length; i++) {
  inputBoxes[i].value = names[i]
}