通过JavaScript查看上传的数组时遇到问题

Question

I am using the File API to upload a file and save its content as a variable in JavaScript. 我正在使用File API上传文件并将其内容另存为JavaScript中的变量。 This is what I have so far but, the result that I get is undefined . 到目前为止，这就是我所得到的，但是我得到的结果是不确定的 。

 <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>

Answer 1

FileReader is asynchronous. FileReader是异步的。 you should set up onload 你应该设置onload

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

通过JavaScript查看上传的数组时遇到问题

问题描述

1 个解决方案

解决方案1
1 已采纳 2016-01-04 05:08:07

通过JavaScript查看上传的数组时遇到问题

问题描述

1 个解决方案

解决方案1 1 已采纳 2016-01-04 05:08:07

解决方案1
1 已采纳 2016-01-04 05:08:07