<div id="box3" style="width: 100px; height: 100px; background-color: orange"></div> <form> <input type="button" id="btn_fadeTo_0" value=".fadeTo('slow', 0)"> <input type="button" id="btn_fadeTo_05" value=".fadeTo('slow', 0.5)"> </form>

$("#btn_fadeTo_05").on("click", function () { $("#box3").fadeTo('slow', 0.5); }); $("#btn_fadeTo_0").on("click", function () { $("#box3").fadeTo('slow', 0); });