<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<script type="text/javascript">
var str = '12345678';
var arr = [];
for (var i = 0;i<8;i++) {
arr.push(str.charAt(i))
}
alert(arr)
</script>
</body>
</html>