👩🏼‍💻바닐라 JS로 크롬 앱 만들기 : #3.3-3.5

## /*#3.3-3.4 Events
:element 를 찾아서 event listener 추가*/
//click event:addEventListener:("click",function)
const title = document.querySelector("div.hello:first-child h1");
function handleTitleClick(){
    console.log("title was clicked");
}
title.addEventListener("click",handleTitleClick);
//("click",handleTitleClick()): 이렇게 하면 바로 실행되기 때문에 자바스크립가 클릭시 해당 함수를 실행하도록 ()제외하고 작성.

### //mouseenter
function handleMouseEnter(){
    console.log("mouse is here");   
}
title.addEventListener("mouseenter", handleMouseEnter);

### //mouseleave
function handleMouseLeave(){
    title.innerText = "mouse is gone"; }

title.addEventListener("mouseenter", handleMouseLeave);
## /*#3.5 More window*/
### //window.resize
function handleWindowResize(){
    document.body.style.backgroundColor = "tomato";
}
window.addEventListener("resize", handleWindowResize);
### //copy 
function handleWindowCopy(){
    alert("copier!");
}
window.addEventListener("copy", handleWindowCopy);  
### //offline,online
function handleWifiOffline(){
    alert("offline!");
}
window.addEventListener("offline", handleWifiOffline);

function handleWifiOnline(){
    alert("online!");
}
window.addEventListener("online", handleWifiOnline);