我正在使用Salesforce的Web-to-lead功能。它基本上创建了一个表单，用于在每次提交的新引导中输入数据。我想知道如何在下面的代码中动态填充隐藏字段（参考网址，着陆页网址，GA源/媒体/广告系列）
我尝试了this blog post上建议的代码，但未成功。
这就是表格形式的html：
<form action="https://www.salesforce.com/servlet/servlet.WebToLead?encoding=UTF-8" method="POST">
<input type=hidden name="oid" value="XXXXXXXXXXXXXXX">
<input type=hidden name="retURL" value="/thankyou.html">
<label for="email">Email</label><input id="email" maxlength="80" name="email" size="20" type="text" /><br>
<label for="first_name">First Name</label><input id="first_name" maxlength="40" name="first_name" size="20" type="text" /><br>
<label for="last_name">Last Name</label><input id="last_name" maxlength="80" name="last_name" size="20" type="text" /><br>
<label for="phone">Phone</label><input id="phone" maxlength="40" name="phone" size="20" type="text" /><br>
<label for="company">Company</label><input id="company" maxlength="40" name="company" size="20" type="text" /><br>
<label for="title">Title</label><input id="title" maxlength="40" name="title" size="20" type="text" /><br>
<div style="display:none;">
<label for="lead_source">Lead Source</label><select id="lead_source" name="lead_source">
<option value="Quotefx Web Inquiry" selected>Web Inquiry</option>
</select><br>
Refer URL:<input id="XXXXXXXXXXXXXX" maxlength="255" name="XXXXXXXXXXXXXX" size="20" type="text" /><br>
Landing Pg URL:<input id="XXXXXXXXXXXXXX" maxlength="255" name="XXXXXXXXXXXXXX" size="20" type="text" /><br>
GA Medium:<input id="XXXXXXXXXXXXXX" maxlength="255" name="XXXXXXXXXXXXXX" size="20" type="text" /><br>
GA Source:<input id="XXXXXXXXXXXXXX" maxlength="255" name="XXXXXXXXXXXXXX" size="20" type="text" /><br>
GA Campaign:<input id="XXXXXXXXXXXXXX" maxlength="255" name="XXXXXXXXXXXXXX" size="20" type="text" /><br>
</div>
<input type="submit" name="submit">
</form>`