SOURCE

file.addEventListener('change', function(){
  var fr = new FileReader;
  fr.onload = function(){
    img.onload = function(){
        
        
      Tesseract.recognize(img,'chi_sim')
      
         .progress(function  (p) { progress.innerText = JSON.stringify(p);    })
         .then(function (result) { window.result.innerHTML = result.html;})
    }
    img.src = this.result;
  }
  fr.readAsDataURL(this.files[0]);
})

<input type='file' id='file'>
<img id='img'>
<script src='https://unpkg.com/tesseract.js@1.0.10/dist/tesseract.js'></script>
<div id='progress'></div>
<div id='result'></div>