svelte/src/shared/_build.js

const fs = require('fs');
const path = require('path');
const acorn = require('acorn');

const declarations = {};

fs.readdirSync(__dirname).forEach(file => {
	if (!/^[a-z]+\.js$/.test(file)) return;

	const source = fs.readFileSync(path.join(__dirname, file), 'utf-8');
	const ast = acorn.parse(source, {
		ecmaVersion: 6,
		sourceType: 'module'
	});

	ast.body.forEach(node => {
		if (node.type !== 'ExportNamedDeclaration') return;

		// check no ES6+ slipped in
		acorn.parse(source.slice(node.declaration.start, node.end), {
			ecmaVersion: 5
		});

		const declaration = node.declaration;
		if (!declaration) return;

		const name = declaration.type === 'VariableDeclaration'
			? declaration.declarations[0].id.name
			: declaration.id.name;

		const value = declaration.type === 'VariableDeclaration'
			? declaration.declarations[0].init
			: declaration;

		declarations[name] = source.slice(value.start, value.end);
	});
});

fs.writeFileSync(
	'src/generators/dom/shared.ts',
	`// this file is auto-generated, do not edit it
const shared: Record<string, string> = ${JSON.stringify(declarations, null, '\t')};

export default shared;`
);