Immediate function using JavaScript ES6 arrow functions

Question

Does anyone know how to write an immediate function using ES6 arrow syntax?

Here's the ES3/5 way of doing it:

(function () {
   //...
}());

I've tried the following but get an unexpected token error on the last line.

(() => {
  //...
}());

You can test this here: http://www.es6fiddle.net/hsb8bgu4/

Answer 1

From the Arrow functions examples,

(() => "foobar")() // returns "foobar" 

So, the function invocation operator should be outside.

(() => {
  //...
})();

Sample: http://www.es6fiddle.net/hsb8s1sj/

Answer 2

Here is my demo codes!

Always remember that function_name+() === function_caller

/* ES5 */

// normal function

function abc(){
    console.log(`Hello, ES5's function!`);
}
abc();

var abc = function xyz(){
    console.log(`Hello, ES5's function!`);
};
abc();

// named function

var abc = function xyz(){
    console.log(`Hello, ES5's function!`);
}();


// anonymous function
// 1
(function(){
    console.log(`Hello, ES5's IIFE!`);
})();

// 2
(function(){
    console.log(`Hello, ES5's IIFE!`);
}());

// 3

var abc = function(){
    console.log(`Hello, ES5's function!`);
}();


/* ES6 */

// named arrow function
const xyz = () => {
    console.log(`Hello, ES6's Arrow Function!`);
};
xyz();


const xyz = (() => {
    console.log(`Hello, ES6's Arrow Function!`);
})();


// Uncaught SyntaxError: Unexpected token (

/*
const xyz = (() => {
    console.log(`Hello, ES6's Arrow Function!`);
}());
*/

// anonymous arrow function
(() => {
    console.log(`Hello, ES6's Arrow Function!`);
})();

Immediately-invoked function expression

let x;

(x = () => {
  console.log(`ES6 ${typeof(x)}`);
})();

// ES6 function

// OR

(() => {
  console.log(`ES6 ${typeof(Symbol)}`);
})();

// ES6 function

Answer 3

Here's a simple example.

To define an arrow function:

const temp = (x)=> {return x+" world";}

// call it as a function
temp("hello") // output: hello world

To make an arrow function immediately invoke:

const temp = ((x)=> {return x+" world";})("hello")

// use it as a variable:
console.log(temp); // output: hello world

// a self-invoking function without params:
const temp = (()=> {return "world";})()