Add a menu item to action menu on CRM FORM

    With the below code you can achieve the above functionality: 

/* Code to add a Button in Action Menu List of a CRM FORM */

/* Code to call a js function on item click */function TestAction() {
    alert("Hi..");
}

if (document.getElementById("_MBTestAction") == null) {
    var elem = document.getElementById("mnuaction");

    var newEle = document.createElement("li");
    newEle.id = "_MBTestAction";
    newEle.className = "ms-crm-MenuItem-Label";
    newEle.tabIndex = -1;
    newEle.action = "TestActionTest();";
    newEle.innerHTML =
"<SPAN class='ms-crm-MenuItem-Label'><A class='ms-crm-MenuLink' tabIndex='-1' onclick='return false;' href='javascript:onclick();' target='_self'><SPAN class='ms-crm-MenuItem-Icon'></SPAN><SPAN class='ms-crm-MenuItem-Text' tabIndex='0'>Do Test Action...</SPAN></A></SPAN>";
    elem.appendChild(newEle);
}

/* Code to add function to the Event Called from Button */

TestActionTest = TestAction;