TypeScript support

Hi,

I want to open a pull request to look at typescript support for this project. The current instructions do not mention that you have to modify the Webpack configuration to use the ‘ts’ extension. The updated documentation is given here below.

const path = require('path');
const { createDefaultConfig } = require('@open-wc/building-webpack');
const merge = require('webpack-merge');

const config = createDefaultConfig({
  input: path.resolve(__dirname, './index.html'),
});

module.exports = merge(config, {
  resolve: {
    extensions: ['.ts']
  }
})

Another solution would also to have typescript support as a optional “opt-in” approach. That would make it easier to use. Happy to do the work and the pull request. Thoughts?

const config = createDefaultConfig({
  input: path.resolve(__dirname, './index.html'),
  withTypeScript: true
});

[abdonrd]

I also propose to have an application template with TS. 😄

[daKmoR]

@difosfor we had an issue in the testing-helper where the typescript declarations files did not end up in the published npm package 🙈 it is solved now 👍 (version 1.6.2)