author: Krasimir Tsonev

Krasimir is a blogger, who writes and speaks.
He loves open source and codes awesome stuff.

My new and shiny tool for live demos - Demoit

I had some time during the weekend and decided to work on my slides for an event at the end of the month. I reached the part where I have to do a live coding session and I was wondering what tool to use. At the end I created my own called Demoit. This is a short article explaining how it works.

demoit

Demoit - a small tool for live coding exercises. Demo here.

The idea

I have to say that I'm not doing a lot of live coding at my talks. I usually create slides with the code so I avoid the stress of writing it in front of people. However, sometimes it feels better if the attendees see how the code actually changes. So, I was going to use one of the popular tools for the purpose - CodeSandbox, JSBin or Codepen. But then I realized that those tools are offering a lot more than I wanted. I was searching for something small that meets my requirements. And, as it often happens with us engineers, I ended up writing my one solution. Here is what I am searching for and what Demoit does at the moment.

  • A nice editor with couple of themes so I feel comfortable writing - I used the well known CodeMirror.
  • No server - I don't want to run a node server every time when I want to do a live coding demo. It is just one more thing that may go wrong and when you are in front of other people this may ruin the whole presentation. I also don't want to use a service that depends on having internet connection. Even though some of the tools that I mention above support offline mode I'm still reserved to such option.
  • Built-in transpilation - Demoit uses Babel as a transpiler. It does the transformation at runtime, in the browser.
  • No dependencies. No building process. Just a simple HTML page and static JavaScript and CSS files - my goal with this is to avoid downloading packages and configuring building process. It's just my code running on top of libraries loaded via <script> tag.
  • Flexible configuration - ability to define my own resources and libraries. For example JavaScript and CSS files that my demo needs.
  • Ability to render to html but also print to the console - this is pretty much trivial for such instruments

The default configuration

Here is how settings.json looks like when you download Demoit.

{
  "editor": {
    "<theme>": "material"
  },
  "dependencies": [
    "./resources/react-16.7.0-alpha.0.js",
    "./resources/react-dom.16.7.0-alpha.0.js",
    "./resources/styles.css"
  ],
  "files": [
    {
      "filename": "script.js",
      "content": "console.log('message');"
    }
  ]
}

In this case the files under the resources field are locally saved on my machine but we can easily use CDN URLs or UNPKG links. Those files are injected into the page before the actual code snippet runs.

Final words

I will be more then happy if you try Demoit and let me know what you think. The demo of this tool for doing demos is available here. If you want to report a bug or who knows maybe doing a pull request go to this URL.

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