ToDo App with WebComponents

ToDo App with WebComponents

As we saw the basics of WebComponents, let see it in action and build a complete ToDo App with WebComponents. Here we will see some of the concepts around WebCompoents and Front-End App.

The benefits of WebComponents App are more or less similar to the benefits of React App; you are free to shape it in any way. So we will be taking React's jargon like props, onClick etc.

Let's dive in the code.

Primarily we have four components

  • todo-application
  • todo-form
  • todo-list
  • todo-task

Among these 4, the first one; todo-application will be hosting everything inside the shadow-dom.

For polyfill, we will be using the official one from webcomponents.org


And for design, we will be using bootstrap 4 CSS.

The app is bundled together with the help of webpack and we will be using babel to transpile our app to ES5 and raw-loader to load css files.

module: {
  rules: [
      test: /\.css$/,
      use: 'raw-loader'
      test: /\.js$/,
      exclude: /(node_modules)/,
      use: {
        loader: 'babel-loader',
        options: {
          presets: ['@babel/preset-env'],
          plugins: [],

As we have it all configured with webpack, lets get into the code for todo app

ToDo App

And template:

Primary things to notice in above code would be:

  • initialize the base data
  • attach a shadowDOM in open mode; you can read more about shadowDOM here
  • set the innerHTML of shadowDOM of its template
  • collect the refs; i.e. the main DOM elements of app
  • set the props on necessary refs
  • define the custom element

For templating, we are using the ES6 template literals. You can read more about them here: https://time2hack.com/2017/12/introduction-to-webcomponents-and-shadowdom/


Following is the Component for form; the form's events are being set manually by the todo app controller after it is mounted be the app controller.

with following HTML as ES6 template:


The List component will receive the object and will use the todo-task component. Here is the component:

And the HTML template for above component:


Following the individual task component which will also handle the completion and depletion of the task:

And the HTML template for above component:

Checkout the code and demo here:

Demo Code

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