var btn=document.getElementById("btn");
btn.onclick=f1;
btn.onmouseover=f1;
btn.onmouseout=f1;
function f1(e) {
switch (e.type) {
case "click":
console.log("click触发");
break;
case "mouseover":
console.log("mouseover触发");
break;
case "mouseout":
console.log("mouseout触发");
break;
}
}