Calling method in Node js from browser (Using Express)

Question

I defined these three routes in app.js

app.use('/', require('./routes/index'));
app.use('/LEDon', require('./routes/LEDon'));
app.use('/LEDoff', require('./routes/LEDoff'));

In my route file I have the following:

var express = require('express');
var router = express.Router();
var Gpio = require('onoff').Gpio,
    led = new Gpio(17, 'out');

router.get('/', function(req, res, next) {
  led.writeSync(1);
});

module.exports = router;

So when I go to the /LEDon page the method runs and everything works. Is it possible though to run a method without using a get request? My main goal is to just click a hyperlink which then runs the method..

Community · Accepted Answer · 2017-05-23 11:47:08Z

15

Essentially you are asking your client side script to directly call a function on your Node server script. The only other choice other than an Ajax POST AFAIK is Socket.io

This similar stackoverflow question should help you out.

edit: I made a simple example spanning multiple files:

/test/app.js:

var express = require('express');
var app = express();

app.post('/LEDon', function(req, res) {
    console.log('LEDon button pressed!');
    // Run your LED toggling code here
});

app.listen(1337);

/test/clientside.js

$('#ledon-button').click(function() {
    $.ajax({
        type: 'POST',
        url: 'http://localhost:1337/LEDon'
    });
});

/test/view.html

<!DOCTYPE html>
<head>
</head>

<body>
    <button id='ledon-button'>LED on</button>
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
    <script src='clientside.js'></script>
</body>

To run it: node app.js in terminal, and open view.html on your browser. Try pressing the button and check out your terminal. Hope this helps.

edited May 23, 2017 at 11:47

CommunityBot

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answered Feb 14, 2015 at 15:22

Keith Yong

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5 Comments

user2255273 Over a year ago

Would you be willing to show me how to use Socket.io when clicking on a hyperlink? I have been looking at Socket.io before but just can't figure it out..

Keith Yong Over a year ago

Sorry I am not familiar with Socket.io. $.ajax would probably be easier. The other answer has a great Ajax answer

user2255273 Over a year ago

Thanks! I ended up using socket.io, which works great. So thanks for pointing me in the right direction.

Josh P Over a year ago

This worked for me! I'm making a telepresence robot and already have the remote controls listening on a UDP port for drive commands (that eventually sends it over Serial to the iRobot Create). So with this I was able to put W A S D keys on my web page and call the server side node.js function to send a UDP message to that command server! Thanks!

user525504 Over a year ago

Can't get this to work on Windows Server. View.html displays 'Cannot GET /view.htm'

siavolt · Accepted Answer · 2015-02-14 15:29:11Z

1

For resolve your problem you can use ajax request, for example:

<body>
    <a onClick=LEDon>LED On</a>
    <a onClick=LEDoff>LED Off</a>

    <script>
    function LEDon(){
       $.ajax({
          url: "http://yourDomain.com/LEDon"
       });
    }

    function LEDoff(){
       $.ajax({
          url: "http://yourDomain.com/LEDoff"
       });
    } 

    </script>
<body>

answered Feb 14, 2015 at 15:29

siavolt

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Comments

RandomX · Accepted Answer · 2020-07-03 10:27:06Z

0

Old question - I know. But as time flies, new ways appear.

Can I suggest trying api-mount. It basically allows calling API as simple functions without having to think about AJAX requests, fetch, express, etc. Basically in server you do:

const ApiMount = apiMountFactory()
ApiMount.exposeApi(api)

"api" is basically an object of methods/functions that you are willing to call from your web application.

On the web application you then do this:

const api = mountApi({baseUrl: 'http://your-server.com:3000'})

Having done that you can call your API simply like this:

const result = await api.yourApiMethod()

Try it out. Hope it helps.

answered Jul 3, 2020 at 10:27

RandomX

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