在通過JavaScript查看上傳的數組時遇到問題

我正在使用File API上傳文件並將其內容作爲變量保存在JavaScript中。這是我迄今爲止的，但是，我得到的結果是undefined。在通過JavaScript查看上傳的數組時遇到問題

<body> 
    <input type="file" id="file" name="file" multiple /> 

    <script> 
     function handleFileSelect(evt) { 

     // grab the file that was uploaded which is type File. 
     // evt is the event that was triggered 
     // evt.target returns the element that triggered the event 
     // evt.target.files[0] returns the file that was uploaded 
     var file = evt.target.files[0]; 

     // instantiate a FileReader object to read/save the file that was uploaded 
     var reader = new FileReader(); 

     // read the file and save as an array 
     fileArray = reader.readAsArrayBuffer(file); 
     window.alert("hello"); 
     window.alert(fileArray); 
     } 

     document.getElementById('file').addEventListener('change', handleFileSelect, false); 
    </script>

來源

2016-01-04 Crt

FileReader是異步的。你應該設置onload

var reader = new FileReader(); 
    reader.onload = function(){ 
      console.log(reader.result); 
     }; 
     // read the file and save as an array 
    reader.readAsArrayBuffer(file);

來源

2016-01-04 05:08:07 Ramanlfc

欣賞的幫助，但它沒有奏效。 – Crt

@Crt控制檯說了什麼 – Ramanlfc

@RamanIfc沒有任何輸出到控制檯 – Crt

在通過JavaScript查看上傳的數組時遇到問題

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