<script type="text/javascript">
var mysz = ["*","##","***","&&","****","##*"];
mysz[7]="**";
alert=(mysz.length);
document.write(mysz[0]+<br/>);
document.write(mysz[7]+<br/>);
document.write(mysz[2]+<br/>);
document.write(mysz[4]);
</script>
<br/>要加上'' alert(mysz.length);不要=
alert后边没有等号
换行符<br/>要加双引号