1.html

<div contenteditable>Press enter<br>http://google.com</div>
<script>
document.onkeydown = function(evt) {
    evt = evt || window.event;
    if (evt.keyCode == 13) { // enter key
        var text = document.querySelector('div').innerHTML;
        var url = text.match(/(HTTP:\/\/)([a-zA-Z0-9.\/&?_=!*,\(\)+-]+)/i);
        var foourl = url[0].replace("http", "foo");
        document.foo = "foo";
        document.http = "http";
        var link =  text.replace(url[0], "<a href='" +
                    foourl +
                    "' style='cursor:pointer' onclick='var http = this.href.replace(document.foo, document.http); window.open(http);return false'>" +
                    url[2] +
                    "</a>");
        document.querySelector('div').innerHTML = link;
    }
};
</script>