JavaScript Image Preview

<html lang="en-GB" xml:lang="en-GB" xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>jQuery Multiple File Uploader</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
  <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css">
  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/dropzone/5.5.1/dropzone.css">


</head>
<body>


  <img id ="img" style="height: 100px; width: 100px;" src="https://images.unsplash.com/photo-1543422521-7dfeaf13cc67?ixlib=rb-0.3.5&ixid=eyJhcHBfaWQiOjEyMDd9&s=9441e9ad49f1726ae85ed2f728eacf26&auto=format&fit=crop&w=1534&q=80" alt="">


  <button id='click' onclick="changeimg()" >Click</button>
<p id="p"></p>


<form action="">
    <input id="input" type="file" value="orko" onchange="preview()">
</form>


<script>


    function preview () {

        var input = document.getElementById("input");
        var fReader = new FileReader();
        fReader.readAsDataURL(input.files[0]);
        fReader.onloadend = function(event){
        //var img = document.getElementById("yourImgTag");
        //img.src = event.target.result;
        document.getElementById('p').innerHTML = event.target.result;

 document.getElementById('img').src = event.target.result;
}
         //document.getElementsByTagName('img')[0].src = document.getElementById('input').value;

            //alert(document.getElementById('input').value);
    }

    function changeimg() {


        //document.getElementById('p').innerHTML = 'lol';
        var link = document.getElementsByTagName('img')[0].src;
    }


</script>


</body>
</html>