transform-es/lib/defaultOptions.js

const defaultsDeep = require("lodash/defaultsDeep");
const fs = require("fs-extra");
const os = require("os");

module.exports = function (options) {
	const browserslist = [
		">=0.25%",
		"not dead",
		"not op_mini all",
		"not Android 4.4.3-4.4.4",
		"not ios_saf < 10",
		// "not ie <= 11",
		"not Chrome < 50", // caniuse lastest is reporting chrome 29
		"firefox ESR",
	];

	const pkgFile = process.cwd() + "/package.json";
	let pkg = {};
	if (fs.existsSync(pkgFile)) {
		pkg = require(pkgFile);
	}

	if (!pkg.browserslist) {
		pkg.browserslist = browserslist;

		fs.writeFileSync(pkgFile, JSON.stringify(pkg, null, 2) + os.EOL);
	}

	const defaults = {
		cwd: process.cwd(), // 工作路径
		glob: ["**/*", "**/*.*", "**/.*"],
		clean: true, //转换前清空输出目录
		watch: false,
		ignore: null,
		filter: null,
		babel: {
			decoratorsBeforeExport: true,
			strictMode: true,
			modules: "commonjs",
			useFlow: true,
			loose: true,
			runtimeOptions: {},
			presets: [],
			plugins: [],
		},
		typescript: {},
		postcss: {},
		eslint: {},
		scss: {},
		less: {},
	};

	return defaultsDeep({}, options, defaults);
};