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Javascript – Reading CSV File without manupulating encoding

I have a csv file that I can see with :

file -bi myCsv.txt

that the character-set is iso-8859-1.
Now I want to read this file using JavaScript from input tag and type ‘file’ without manipulating the encoding.

I tried several options with FileReader() with a method readAsText() and readAsArrayBuffer() or with a fetch API and new Uint8Array(arrayBuffer), but every time I send the file (as string or byte[]) to the backend via ajax-post-request, I see UTF-8 and not iso-8859-1 anymore.

I thought that if I read just a bytes of this file, i would not manipulate the encoding.
But with FileReader() and fetch-API(URL) the encoding is changed every time.
How can i read text files without changing the encoding to check the encoding in the backend, which works fine.

Here is Update, when i’am sending that as byte[] 

async function sendFileToValidation() {
      const file = document.getElementById("uploadFile").files[0];
      try {
        const fileURL = URL.createObjectURL(file);              
        const response = await fetch(fileURL); //no idea, which encoding is set
        const arrayBuffer = await response.arrayBuffer();
        const byteArray = new Uint8Array(arrayBuffer);       
        $.ajax({
          url: '/validateOnBackend',
          type: 'POST',
          contentType: 'application/octet-stream',
          data: byteArray,
          success: function (response) {
            alert("we can process this encoding!!!!" + response);
          },
          error: function (xhr, status, error) {
            alert("Error: " + xhr.responseText);
          }
        });

        return byteArray;
      } catch (error) {
        console.error('error', error);
      }

    }
Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    I solved my problem. I've used FileReader.readAsArrayBuffer. And then i converted this to byte-array with new Uint8Array(arrayBuffer) and after that i send it as json like: JSON.stringify(Array.from(byteArray));


  2. 0

    You need the second, optional encoding parameter to readAsText detailed here.

    document.getElementById("fileInput").addEventListener("change", function (event) {
    const file = event.target.files[0];
    const reader = new FileReader();

    // Read the file as ISO-8859-1
    reader.readAsText(file, "iso-8859-1");

    reader.onload = function () {
        document.getElementById("output").textContent = reader.result;
    };

    reader.onerror = function () {
        console.error("Error reading file:", reader.error);
    };
});
    <input type="file" id="fileInput" />
<pre id="output"></pre>
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