Question

I use node.js and express. When I press the button (btnSend), I want to send data to node.js by express (without refresh the page). How do I send data using jQuery?

<form action="/Send" method="post">
Username: 
<input type="text" name="user" id="txtUser" />
<input type="submit" value="Submit" id="btnSend" />
</form>

Answer 1

Here’s a rough outline of what your jQuery should look like:

$("form").submit(function(e) {
    e.preventDefault(); // Prevents the page from refreshing
    var $this = $(this); // `this` refers to the current form element
    $.post(
        $this.attr("action"), // Gets the URL to sent the post to
        $this.serialize(), // Serializes form data in standard format
        function(data) { /** code to handle response **/ },
        "json" // The format the response should be in
    );
});

This code snippet finds all form elements on the page and listens for a submit event from them. A form can be submit in a number ways (e.x. clicking a submit button, hitting enter, etc…), so for the sake of usability, it’s best to listen for submit events directly opposed to listening for click events key on submit buttons.

When a submit event does occurs, the code above first prevents the default browser actions (which among other things refreshes the page) by calling e.preventDefault. It then uses $.post to send the form data to the url specified in the action attribute. Note that $.fn.serialize is used to serialize the form data in a standard format.

Your express code should look something like this:

var express = require('express')
  , app = express.createServer();

app.use(express.bodyParser()); // Automatically parses form data

app.post('/Send', function(req, res){ // Specifies which URL to listen for
  // req.body -- contains form data
});

app.listen(3000);

The documentation on express.bodyParser is a bit sparse, but after a bit of code spelunking it looks like it uses node-querystring underneath the covers.

Hope this helps!