Pure JS copy text

helper.js

function copyText(value) {
  let fakeElem = document.createElement('TEXTAREA')
  fakeElem.style.position = 'absolute'
  fakeElem.style.left = '-9999px'
  fakeElem.style.top = (window.pageYOffset || document.documentElement.scrollTop) + 'px'
  fakeElem.readonly = true
  fakeElem.value = value
  document.body.appendChild(fakeElem)
  fakeElem.focus()
  fakeElem.setSelectionRange(0, value.length)
  try {
    document.execCommand('copy')
  } catch (err) {
    console.log('不支持复制: ' + err.message)
  }
  fakeElem.blur()
  document.body.removeChild(fakeElem)
}