<!DOCTYPE html>
<html>

<head>
    <meta charset="UTF-8">
    <style>
       /* 填写样式 */
    </style>
</head>

<body>
    <!-- 填写标签 -->
    <script type="text/javascript">
        // 填写JavaScript
     
  const _isCard = number => {
    if(number.length!==18){
        return false
    }else{
        let arr=number.split('')
        arr.pop()
     let flag=arr.every((item,index)=>{
      var code=number.charCodeAt(index)
      return code>=48&&code<=57
     })
  
      if(flag){
let arr0=number.split('')
let code0=number.charCodeAt(number.length-1)

if(code0>=48&&code0<=57){
    return true
}else if(arr0[arr0.length-1]==='X'){
    return true
}else{
    return false
}
     }else{
        return false
     }
    }
       
    }


    </script>
</body>

</html>