my$(“btn”).onclick = f1;
    my$(“btn”).onmouseover = f1;
    my$(“btn”).onmouseout = f1;
    function f1(e) {
    switch (e.type) {
    case “click”:
    alert(“好帅哦”);
    break;
    case “mouseover”:
    this.style.backgroundColor = “red”;
    break;
    case “mouseout”:
    this.style.backgroundColor = “green”;
    break;
    }
    }