itsa-browser-portscan

Lightweight Port Scanner that works in the browser.

No dependencies

How it works:

itsa-browser-portscan creates an Image Element and set its source to the defined host and port, without manipulating the DOM. If the port is opened, the image onload or onerror event will be called within 10 seconds. Port 80 and 443 will call the onload, while other ports call onerror. In case a port is closed, no callback happens: the module uses a 10 second timeout to determine that in those cases the port is closed. The image will be removed from the dom once the Promise is ready.

The only method itsa-browser-portscan provides is checkPortStatus(). It returns a Promise with either true or false.

• Open ports 80 and 443 will resolve true almost immediattely
• Other open ports will resolve true after 5-8 seconds
• Closed ports will resolve false after 10 seconds

How to use:

const checkPortStatus = require('itsa-browser-portscan');

const checkPort = async (host, port) => {
    try {
        portOpen = await checkPortStatus(host, port);
        console.log(`${host}:${port} open: ${portOpen}`);
    }
    catch (err) {
        console.warn(err);
    }
};

checkPort('mydomain.com', 3000);

// or, use the 3rd argument to overrule the default timeout of 10000 miliseconds for determining closed ports:
// checkPort('mydomain.com', 3000, 15000);

Code is licensed under the New BSD License.