In an HTML-document, i want to have a (if possible: invisible) form that POSTs the contents of one text input field to my server as soon as the document is created or if possible within s seconds. The document is created via javascript's open.
How can i do that?
No matter what you are trying to do :) you can submit the form any time like this with javascript:
document.form_name.submit();
Let's say you want to submit the form as soon as page loads, you can do like:
<head>
<script type="text/javascript">
window.onload = function(){
document.form_name.submit();
};
</script>
</head>
You may want to use some of the AJAX magic here.
You can achieve this by by using a POST request for getting the client communicate some data to the server.
I recommend reading this jQuery AJAX Tutorial.
The XMLHttpRequest object (the object responsible for nifty AJAX things like Google maps and Gmail) allows for invisible communication with your server from the browser. I recommend using some AJAX library to cover the cross-browser differences. THe most popluar one is Jquery, which allows code like this:
$.post('/path/to/script.php', {
"key": "Value",
"anotherkey": "it's value"
}, function (dat){
//this function will be called when it is succesful
//the variable dat is populated witht he server's response.
});
This allows for simple seamless communication with the browser.