5. javascript 函數

一、姓名取代

function formatName(name) {
  let newStr;
  if (name.length === 2) {
  newStr = name.substr(0, 1) + '*';
  } else if (name.length > 2) {
    let char = '';
    for (let i = 0, len = name.length - 2; i < len; i++) {
      char += 'O';
    }
    newStr = name.substr(0, 1) + char + name.substr(-1, 1);
  } else {
    newStr = name;
  }

  return newStr;
}