console.log()换行和document.write()换行
<!DOCTYPE html>
<html >
<head>
<meta charset="utf-8">
<title>dddd</title>
</head>
<body>
<script type="text/javascript">
var mya = new Array(3);
mya[0] = "1";
mya[1] = "2";
mya[2] = "3";
var a=mya.concat("=","5");
document.write(a+"<br>");
document.write(a[0]+"<br>"+a[1]+"<br>"+a[2]+"<br>"+a[3]+"<br>"+a[4]);
console.log(a+"\n");
console.log(a.length);
</script>
</body>
</html>
