php有办法实现像这样输出js代码？该怎么解决

php有办法实现像这样输出js代码？
比如有个变量值是这样的

PHP code

$a = "<script>window.location.href='http://xxx.com';</script>";

Assembly code

<script>window.location.href='http://xxx.com';</script>

HTML code

<script>window.location.href='http://xxx.com';</script>

PHP code

$a = "<script>window.location.href='http://xxx.com';</script>";$b = htmlspecialchars($a);echo $b;//result: <script>window.location.href='http://xxx.com';</script> //source: &lt;script&gt;window.location.href='http://xxx.com';&lt;/script&gt;