get the data of uploaded file in javascript

you can use the new HTML 5 file api to read file contents

https://developer.mozilla.org/en-US/docs/Using_files_from_web_applications

but this won't work on every browser so you probably need a server side fallback.


The example below is based on the html5rocks solution. It uses the browser's FileReader() function. Newer browsers only.

See http://www.html5rocks.com/en/tutorials/file/dndfiles/#toc-reading-files

In this example, the user selects an HTML file. It is displayed in the <textarea>.

<form enctype="multipart/form-data">
<input id="upload" type=file   accept="text/html" name="files[]" size=30>
</form>

<textarea class="form-control" rows=35 cols=120 id="ms_word_filtered_html"></textarea>

<script>
function handleFileSelect(evt) {
    let files = evt.target.files; // FileList object

    // use the 1st file from the list
    let f = files[0];
    
    let reader = new FileReader();

    // Closure to capture the file information.
    reader.onload = (function(theFile) {
        return function(e) {
          
          jQuery( '#ms_word_filtered_html' ).val( e.target.result );
        };
      })(f);

      // Read in the image file as a data URL.
      reader.readAsText(f);
  }

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

The example below shows the basic usage of the FileReader to read the contents of an uploaded file. Here is a working Plunker of this example.

function init() {
  document.getElementById('fileInput').addEventListener('change', handleFileSelect, false);
}

function handleFileSelect(event) {
  const reader = new FileReader()
  reader.onload = handleFileLoad;
  reader.readAsText(event.target.files[0])
}

function handleFileLoad(event) {
  console.log(event);
  document.getElementById('fileContent').textContent = event.target.result;
}
<!DOCTYPE html>
<html>

<head>
  <script src="script.js"></script>
</head>

<body onload="init()">
  <input id="fileInput" type="file" name="file" />
  <pre id="fileContent"></pre>
</body>

</html>