javascript - 将所有背景更改为透明

Question

https://codepen.io/jayllopy/pen/bQgRPY

function openNav() {
document.getElementById("mySidenav").style.width = "250px";
document.getElementById("main").style.marginLeft = "250px";
document.body.style.backgroundColor = "rgba(0,0,0,0.4)";
}

function closeNav() {
document.getElementById("mySidenav").style.width = "0";
document.getElementById("main").style.marginLeft= "0";
document.body.style.backgroundColor = "white";
}

我有这个链接将所有背景更改为白色不透明度0.4，除了#main，bg颜色为红色

问：我想在 sidenav 打开时将#main 背景更改为 rgba(0,0,0,0.4)

Answer 1

function openNav() {
    document.getElementById("mySidenav").style.width = "250px";
    document.getElementById("main").style.marginLeft = "250px";
    document.getElementById("main").style.backgroundColor = 'rgba(0,0,0,0.4)';
}

function closeNav() {
    document.getElementById("mySidenav").style.width = "0";
    document.getElementById("main").style.marginLeft= "0";
    document.body.style.backgroundColor = "white";
    document.getElementById("main").style.backgroundColor = 'rgb(255,0,0)';
}

当你关闭它时它会变回红色。