Here is a simple webpage that I wrote to test HTML code in real time as typed, what are some ways that I can Improve my code? part of the code is reused from a previous project, I believe that it may now be causing problems. I am still learning about CCS and in places i used both the HTML width tag and the CCS property to set the width of the item. When searching stackoverflow I found Quite a few questions about how HTML code can be loaded into an iframe, this seems to be a common problem, Am I properly loading a HTML string into an iframe?<!DOCTYPE html><title>Live HTML tester</title><h1 id=Pagetitle>Live HTML tester</h1><html>    <head>    </head><style>h1{    text-align: center;}textarea{    vertical-align: top;    width:100%;}iframe{    vertical-align: bottom;    width:100%;}</style><body>    <input id=browseOpen type=file accept=.html/>    <textarea         rows=20         id=HTMLdata        placeholder=Enter HTML code        onKeyPress=edValueKeyPress()         onKeyUp=edValueKeyPress()>    </textarea>    <iframe id=test_iframe src=about:blank width=100% height=400></iframe></body><script language=javascript>    var fileInput = document.getElementById(browseOpen);    fileInput.onchange = function() {        var fr = new FileReader();        fr.onloadend = function() {            var result = this.result;            html_string = result;            //alert(result);            var TheText = document.getElementById(HTMLdata);            TheText.innerText=result;            edValueKeyPress();        };        fr.readAsBinaryString(this.files[0]);    };    function edValueKeyPress(){        var edValue = document.getElementById(HTMLdata);        var html_string = edValue.value;        var iframe = document.getElementById('test_iframe');        var iframedoc = iframe.document;            if (iframe.contentDocument)                iframedoc = iframe.contentDocument;            else if (iframe.contentWindow)                iframedoc = iframe.contentWindow.document;         if (iframedoc){             iframedoc.open();             iframedoc.writeln(html_string);             iframedoc.close();         } else {            alert('Cannot inject dynamic contents into iframe.');         }    }</script></html>Here is where the page is being hosted LiveHTML.html
Real time HTML tester
javascript;html;css