JSFiddle - React, Tailwind, and code Playground

HTML

<input type="file" id="myInput">

<div class="ctn">
  <span class="bold">mimetype:</span><span id="result"></span>  
</div>

CSS

.ctn {
  margin-top: 20px;
}
.bold {
  font-weight: bolder;
  margin-right: 4px;
}

JavaScript

myInput.onchange = function() {
  result.innerHTML = this.files[0].type;
}