Consider you have the following form:
<form id="register"action="/register" method="post">
<input type="text" name="first_name"/>
<input type="text" name="last_name"/>
<input type="text" name="email"/>
<input type="submit" value="register"/>
</form>
Your client side JavaScript could look like this:
var form = document.getElementById("register");
form.addEventListener("submit", function() {
// ajax call
// prevent the submit
return false;
});
On server side you would be able to access the form data:
app.post("/register", function(req, res) {
var user = {
first_name : req.body.first_name,
last_name : req.body.last_name,
email : req.body.email
};
});
For further reading:
How to prevent form from being submitted?