Copy URL To Clipboard On Npm Run Start

How to copy the start URL and parameters of your application to your clipboard while starting it locally.

Dec 11, 2020

#javascript #webdev #nodejs #npm

Photo by Gia Oris on Unsplash

I am not sure anyone will ever need the following tricks but, at my client’s place, we have an application which can only be accessed through an URL which contains a dynamic base64 parameter. Needless to say, it makes its local development a bit inconvenient.

In addition, I have to admit, I am not a big fan of CLI’s options which can automatically open browser. Even though I mostly use the Chrome Incognito mode for development purpose, I like to switch often between browsers to try out what I developed.

Finally, I don’t use bookmarks (don’t judge me) and, I often switch between technologies. Therefore, without configuration, every time another port has to be used ( :3333 or :4200 or :8000 or :8100 etc.).

That’s why I had the idea to add a pre-start script to the application which should copy the start URL of the application to my clipboard. Doing so, I can then just select a browser, paste the URI and, I am good to go.


In order to copy or read value to the clipboard from a NodeJS script, I used the library clipboardy which implement such a cross-platform feature.

In addition, I also added chalk ann boxen to print out the URL to the console in a stylish way.

You may notice that all these dependencies are open source and developed by the same person, Sindre Sorhus, which definitely deserve a shout-out for this awesome contribution and work 👍.

npm i clipboardy chalk boxen --save-dev


Once the dependencies fetched, I created the pre-start script itself. In this example, I create a file start-url.js at the root of the project.

The script primary generates the url which I am looking to copy in my clipboard. On purpose, I am using an Hello World 👋 string to demonstrate that it is possible to encode complex parameters.

To print out a nice message, I use chalk with colors, in for- and background, and the bold option. I use \n\n to create newlines. It is worth to notice that the library offer many options such as combining or nesting styles.

Using clipboardy to copy the URL to the clipboard is actually really few work and can be solved by calling its function copy with the all URL as input parameter.

Finally, in a console.log , I print out the message inside a box generated with boxen .

const { write: copy } = require("clipboardy"); const chalk = require("chalk"); const boxen = require("boxen"); const params = encodeURIComponent("Hello World 👋"); const url = `http://localhost:3333/profile/${params}`; (async () => { let message = chalk.yellow.inverse("Your URL"); message += `\n\n${chalk.bold(`${url}`)}`; try { await copy(url); message += `\n\n${chalk.grey("Copied local address to clipboard!")}`; } catch (err) { message =`Cannot copy ${url} to clipboard 🥺\n\n${err.message}`); } console.log( boxen(message, { borderStyle: "round", padding: 1, borderColor: "yellow", margin: 1 }) ); })();

Life Cycle

Thanks to npm it is possible to execute scripts at different life cycles. Because I was looking to copy the URL when I start locally the application, I added it as a prestart script to my package.json.

"scripts": { "prestart": "node start-url.js" }

You might ask “But David, why a prestart and not poststart?” to which I would answer that prestart is executed for sure. On the contrary, poststart, is indeed also executed but, only when the start life cycle would be released. If your local server, as often, would stay active to watch for changes, poststart would only resolve when you would cancel your local server.


Everything being in place, when I hit npm run start in my console, the URL is generated, copied to the clipboard and, I notice the following output.

If I open one of my browser, I can paste the result in the navigation bar.

Finally, hit enter and access my URL with the generated parameters.


As underlined in the introduction of this post, I am really not sure if anyone will ever need this solution ever 😅. Anyway, I hope it was a fun read and let me know if you would improve anything.

To infinity and beyond!