Subida de imágenes con previo

index.html

<input type='file' onchange="previewImage(this, 'preview-image');" />
<img id="preview-image" src="http://placehold.it/300" alt="image preview" />

scripts

     function previewImage(input, container) {
            if( input.files.length < 1) {
              return ;
            }
       
           var reader = new FileReader();

           reader.onload = function (e) {
             document.getElementById(container).src = e.target.result;
           };

           reader.readAsDataURL(input.files[0]);
        }

styles.css

img#preview-image{
  max-width:300px;
}

input[type=file]{
 padding:10px;
 background:#2d2d2d;
}