title: VBScript slow byte array copy
body: <p>I am using the following code to read in a binary file in VBScript and store it in a byte array which I then access from Javascript and copy to a JS array, basically just a sneaky way (the only way!) i've found of reading binary data in my JS.</p>
  
  <pre><code>Function readBinaryFile(fileName)
      dim inStream,buff
  
      set inStream=CreateObject("ADODB.Stream")
      inStream.Open
      inStream.type=1
  
      inStream.LoadFromFile fileName
  
      buff=inStream.Read()
      inStream.Close
  
      Dim byteArray()
  
      Dim i
      Dim len
      len = LenB(buff)
  
      ReDim byteArray(len)
  
      For i = 1 To len
          byteArray(i-1) = AscB(MidB(buff, i, 1))
      Next
  
      readBinaryFile=byteArray
  End Function
  </code></pre>
  
  <p>It appears to work exactly as expected, the only problem being it seems extremely slow. For example, reading in a 300kb file can take over 2 minutes. I am expecting to read files up to around 2meg.</p>
  
  <p>Could anyone explain why this is such a slow operation and if there's anything I can do to speed it up?</p>
  
  <p>Thanks.</p>