Edit in JSFiddle

<div class="myDiv">This is div element</div>
<p>This is paragraph element</p>
<div class="myDiv">This is div element</div>
<p>This is paragraph element</p>
<div class="myDiv">This is div element</div>
<div class="myDiv">This is div element</div>

$(document).ready(function () {
    $("div.myDiv").css("color", "red");
});