WAT-the-CAT.js

// Standard fat-arrow function stored 
// as a variable and immediatelly called. 
> let foo = () => {return '😹'}; foo() 
< "😹"

// If there is no block, then JS will 
// Implicitly return whatever is the 
// result of given statement. 
> let foo = () => '😹'; foo()
< "😹"
 
// So what If we want to implicitly 
// return a hash? 
> let foo = () => {cat: '😹'}; foo()
< undefined 
// It does not work, because first lexical 
// meaning of curly brackets is a block. 
// And 'cat' in this case will be a label. 

// So to do an implicit return of a hash, 
// we have to wrap the hash in parentheses. 
> let foo = () ({cat: '😹'}); foo()
< {cat: "😹"}

// We can also call the function directly, 
// without storing it. But to do that we 
// have to wrap the whole function into 
// parentheses. 
> let foo = (() => ({cat: '😹'})))()
< {cat: "😹"}

// And what if now we just want the emoji 
// of the cat? We can destructure 
// the returned hash. 
> let {cat} = (() => ({cat: '😹'}))(); cat
< "😹"