html,body { height: 100%; overflow: hidden; background: black; -webkit-user-select: none; } ul { list-style-type: none; padding: 0; margin-left: 12px; } ul >li { width: 40px; height: 40px; border-radius: 50%; opacity: 0.3; display: inline-block; } ul.red >#red, ul.green >#green, ul.yellow >#yellow { opacity: 1.0; } #red {background: red;} #yellow {background: yellow;} #green {background: lime;} </style>
<title>js red green light</title> <body> <ul id="traffic" class="green"> <li id="green"></li> <li id="yellow"></li> <li id="red"></li> </ul> </body>
setInterval(function(){ setTimeout(function(){ traffic.className='green'; setTimeout(function(){ traffic.className='yellow'; setTimeout(function(){ traffic.className='red'; },500) },500) },500) },1500)