console.log("%c%s",
"color: red; background: yellow; font-size: 24px;",
"WARNING!");console.log('hello')
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Page Title</title>
</head>
<body>
<script>
// Your JavaScript goes here!
console.log("Hello, World!")
</script>
</body>
</html><script>
console.log(x); // return undefined
var x="hello js";
console.log(x); // return "hello js"
</script>
console.log("red)