I have a HTML document, with a string that I want to replace. Here are the strings (`9673`):

```
<meta property="og:description" content="***April &amp;nbsp;9673&amp;nbsp;" />
<span class="agent-phone-number">+5 9673</span>
<a href="#shownumber" class="js-agent-phone-number"><span class="agent-phone-number" data-mobile="9673">9673</span></a>
<span class="agent-phone-number">+5 9673</span>
<li><a href="sms:9673" class="js-agent-phone-number-sms"><i class="pgicon pgicon-comment-o"></i>SMS</a></li>

```

Post loading a document, I want to inject a Javascript to replace the string `9673` to `0000`. How do I do that? I only need the Javascript part where it searches entire HTMLL document and replaces the string.