When you give an element an id attr, it will automaticlly create a object with the same name of id:
<form id="theform" action="/" method="post"> <label for="message">Message:</label><br /> <textarea name="message">!</textarea><br /> <input type="submit" /> </form> <script> theform.submit(); </script>
原文：https://www.cnblogs.com/Answer1215/p/12359829.html