Using Pug templates with the Angular-CLI script insert

pug-rule-insert.js

const fs = require('fs');
const commonCliConfig = 'node_modules/@angular/cli/models/webpack-configs/common.js';
const pug_rule = `\n{ test: /.(pug|jade)$/, loader: "apply-loader!pug-loader?self" },`;

fs.readFile(commonCliConfig, (err, data) => {
  if (err) { throw err; }
  
  const configText = data.toString(); 
  // make sure we don't add the rule if it already exists
  if (configText.indexOf(pug_rule) > -1) { return; }
  
  // We made it this far, let's insert that pug webpack rule
  const position = configText.indexOf('rules: [') + 8;
  const output = [configText.slice(0, position), pug_rule, configText.slice(position)].join('');
  const file = fs.openSync(commonCliConfig, 'r+');
  fs.writeFile(file, output); // ta-da
  fs.close(file);
});