packages/hast-util-is-javascript/index.js
function check(value, prefix) {
  var val

  if (typeof value !== 'string') {
    return false
  }

  val = trim(value.split(';', 1)[0]).toLowerCase()

  return val === '' || mime.indexOf((prefix || '') + val) !== -1
}
function check(value, prefix) {
  var val

  if (typeof value !== 'string') {
    return false
  }

  val = trim(value.split(';', 1)[0]).toLowerCase()

  return val === '' || mime.indexOf((prefix || '') + val) !== -1
}
Check one value.