Disable approve/reject using Jquery in ribbon and context menu if item is already approved

Hello,

Need help on disabling approve/Reject button in ribbon(and context menu) if the item is already Approved. This is what i have tried so far:

var ApprovalStatus = SPUtility.GetSPField('Approval Status').GetValue();
		alert($(A[name = 'SPBookmark_ApprovalStatus'].Value()));
		var edit = document.getElementById("Ribbon.ListForm.Display.Manage.ApproveReject-Medium");
        edit.style.display = "none";