file preview by javascript. Reaaaaaally rocks!

FilePreview

// html

<form id="form1" runat="server">
  <input type='file' id="imgInp" />
  <img id="blah" src="#" alt="your image" />
</form>

// javascript

function readURL(input) {
  if (input.files && input.files[0]) {
    var reader = new FileReader();
            
    reader.onload = function (e) {
      $('#blah').attr('src', e.target.result);
    }
            
    reader.readAsDataURL(input.files[0]);
  }
}
    
$("#imgInp").change(function(){
  readURL(this);
});