Web.TextControl provides a code-behind API to load and save documents from and to the server. Additionally, local files can be loaded using drag and drop on the control workspace.

Client-side, the Javascript API also provides a method to load local files:

TXTextControl.loadDocument(streamType, base64Data);

This sample shows how to open a local document with the HTML Input element and how to pass this document as a Base64 encoded string to the loadDocument method.

On selecting a new document in the Input element, the document is loaded into a FileReader that asynchronously reads the contents of files. The method readAsDataURL converts the document to a Base64 encoded string automatically. Based on the file extension, the required StreamType is recognized and finally loaded into TX Text Control.

// *****************************************************************
// readDocument
//
// Desc: This function reads a file, converts it to a Base64 encoded
// string and loads it into TX Text Control
//
// param input: The input HTML element
// *****************************************************************
function readDocument(input) {
 if (input.files && input.files[0]) {
  var fileReader = new FileReader();
  fileReader.onload = function (e) {

   var streamType = TXTextControl.streamType.PlainText;

   // set the StreamType based on the lower case extension
   switch (fileinput.value.split('.').pop().toLowerCase()) {
    case 'doc':
     streamType = TXTextControl.streamType.MSWord;
     break;
    case 'docx':
     streamType = TXTextControl.streamType.WordprocessingML;
     break;
    case 'rtf':
     streamType = TXTextControl.streamType.RichTextFormat;
     break;
    case 'htm':
     streamType = TXTextControl.streamType.HTMLFormat;
     break;
    case 'tx':
     streamType = TXTextControl.streamType.InternalUnicodeFormat;
     break;
    case 'pdf':
     streamType = TXTextControl.streamType.AdobePDF;
     break;
   }

   // load the document beginning at the Base64 data (split at comma)
   TXTextControl.loadDocument(streamType, e.target.result.split(',')[1]);
  };

  // read the file and convert it to Base64
  fileReader.readAsDataURL(input.files[0]);
 }
}

// call readDocument when a new document has been selected
$("#fileinput").change(function () {
 readDocument(this);
});

Download the sample from GitHub and test it on your own.