React Hello World App

• install dependencies via command line npm install
• start development server with command npm run start:dev
• build your app using npm run build command, your build appears in dist folder

Some useful commands

npm run codestyling:fix fixes code styles automatically end show errors that not convenient for eslint rules

npm run eslint:check checks the code according to eslint rules

npm run prettier:check checks the code according to prettier rules

Last two of the commands are useful for ci/cd tools.

Test

it uses jest for testing. run this command for run tests: npm run test

Enabled Babel Plugins

• @babel/plugin-proposal-class-properties which enables add properties and bound functions in classes directly. doc

• @babel/plugin-proposal-export-default-from

export v from 'mod';

• @babel/plugin-proposal-export-namespace-from

export * as ns from 'mod';

• @babel/plugin-proposal-logical-assignment-operators

a ||= b;
obj.a.b ||= c;

a &&= b;
obj.a.b &&= c;

• @babel/plugin-proposal-nullish-coalescing-operator

var foo = object.foo ?? "default";

• @babel/plugin-proposal-optional-chaining

const obj = {
  foo: {
    bar: {
      baz: 42,
    },
  },
};

const baz = obj?.foo?.bar?.baz; // 42

const safe = obj?.qux?.baz; // undefined

// Optional chaining and normal chaining can be intermixed
obj?.foo.bar?.baz; // Only access `foo` if `obj` exists, and `baz` if
                   // `bar` exists

// Example usage with bracket notation:
obj?.['foo']?.bar?.baz // 42

• @babel/plugin-proposal-throw-expressions

function test(param = throw new Error('required!')) {
  const test = param === true || throw new Error('Falsy!');
}

• @babel/plugin-proposal-function-bind doc

enables function context binding with :: instead of .bind

obj::func
// is equivalent to:
func.bind(obj)

::obj.func
// is equivalent to:
obj.func.bind(obj)

obj::func(val)
// is equivalent to:
func.call(obj, val)

::obj.func(val)
// is equivalent to:
obj.func.call(obj, val)

• @babel/plugin-transform-regenerator

enables generator feature

function* a() {
  yield 1;
}

• @babel/plugin-proposal-json-strings
• @babel/plugin-proposal-function-sent
• @babel/plugin-syntax-dynamic-import
• @babel/plugin-syntax-import-meta