create a gui function from filw in javascript

To create a GUI function in JavaScript that reads a file, follows these steps:

1. Create an HTML file input element with an event listener that calls a JavaScript function when a file is selected.
2. In the JavaScript function, use the FileReader API to read the contents of the selected file as a string.
3. Depending on your use case, you can then display the contents of the file in your GUI, manipulate the string data, or otherwise process it as needed.

Here's sample code that demonstrates this process:

<!-- HTML code -->
<input type="file" id="input-file" onchange="readFile()">
<div id="output"></div>
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index.tsx
// JavaScript code
function readFile() {
  const input = document.getElementById("input-file");
  const reader = new FileReader();
  reader.readAsText(input.files[0]);
  reader.onload = function() {
    const contents = reader.result;
    // Do something with the file contents
    document.getElementById("output").innerHTML = contents;
  };
}
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This code creates an HTML file input element that calls the readFile() function when a file is selected. The readFile() function creates a new FileReader object, reads the selected file as a text string, and then sets the innerHTML property of an output div element to the file contents. Of course, you could modify this code to suit your specific needs, such as by processing the file contents with regular expressions or using a different type of input element.