EcmaScript6のハマり記法問答集（変数編） ref: http://qiita.com/inuscript/items/03b5affa614c50d72d5a

file0.js

var a = "hoge" // もう忘れていい
let b = "fuga" // 変更できる値。mutable
const c = "baz" // 変更できない値。immutable

file1.js

let hoge = "fuga"

let obj = {
    hoge
}

console.log(obj) 
// { hoge: "fuga" }

file2.js

const { hoge } = obj

console.log(hoge)
// "fuga"

file3.js

let a = {
  b : {
    c : "d"
  }
}

let { b : { c } } = a
console.log(c) // "d"
console.log(b) // undefined

file4.js

let fooFn = function({ hoge, fuga }){
    console.log(hoge, fuga)
}

fooFn({
    hoge: "aaa",
    fuga: "bbb"
}) 
// aaa, bbb

file5.js

let foo = "baz"
let bee = "boo"
retrun <Cmp { ...{ foo, bee } } />
// <Cmp foo={foo} bee={bee} /> と同じ

file5.txt

let foo = "baz"
let bee = "boo"
retrun <Cmp { ...{ foo, bee } } />
// <Cmp foo={foo} bee={bee} /> と同じ

file6.js

let a = 1
let b = 2
let c = { a, b }
let d = { ...{ a, b } }

console.log(c) 
console.log(d) 
// どっちもこうなる{ a: 1, b:2 }

file7.js

let b = "foo"
let a = { [b] : "baz" }
// a = { foo: "baz" }

file7.txt

let b = "foo"
let a = { [b] : "baz" }
// a = { foo: "baz" }