Edit in JSFiddle

$(document).ready(function () {
    $(document).on('click', '#setHtml', function (event) {
      var content=$(".test").html("Set with html() ");
    });
});

<h1>Jquery html() to set the content</h1>
<div class="test">
This is a content to replace
 </div>

<input type="submit" value="set Html" id="setHtml" />