请问js里面写js的问题

[伊能静]

<script>
document.write("<script> if (typeof(pic)!='undefined') {document.write ('<a target=_blank href=http://123.com'+pic+'><br>');}</script>");
</script>

上面这样错误。正确的应该怎样？谢谢。

[xshf12345]

<script>
document.write("\<script\>alert('sdf')\<\/script\>");
</script>

[wwq0123]

加斜杠
<script>
document.write("<script> if (typeof(pic)!='undefined') {document.write ('<a target=_blank href=http://123.com'+pic+'><br>');}<\/script>");
</script>