字符串包含双字节字符时如何遍历

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  <title></title>
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<body>
  <div >
  </div>
  <script>
    let message = 'x????u'
    //无法访问“????”
    for (let i = 0; i < message.length; i++) {
      console.log(message[i])
    }
    //无法访问“????”
    for (let i in message) {
      console.log(message[i])
    }
    //可以访问“????”
    for(let item of message) {
      console.log(item)
    }
    //可以访问“????”
    let arr1 = [...message]
    arr1.forEach(item => {
      console.log(item)
    })
    //可以访问“????”
    let arr2 = [...message]
    for (let i = 0; i < arr2.length; i++) {
      console.log(arr2[i])
    }
  </script>
</body>
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字符串包含双字节字符时如何遍历