js 數組與對象的解構賦值

解構賦值是javascript 語法，作用是將值從數組、或屬性從對象，提取到不同的變量中。

1. 數組解構
		1.1 聲明變量並賦值：
			let hi = ['hello', 'world'];
			let [hello, world] = hi
			console.log(hello) => hello
			console.log(world) => world
			
		1.2 設置解構默認值
			let hi = 'hello world';
			let [hello, world = 'hi'] = hi
			console.log(hello) => hello world
			console.log(world) => hi
			
		1.3 使用擴展運算符解構
			function f () {
				return ['hello', 'world', 'my', 'name', 'is Lilei'];
			}
			let [hello, world, ...who] = f()
			console.log(hello) => hello
			console.log(world) => world
			console.log(who) => ['my', 'name', 'is Lilei']
			
		1.4 忽略某些返回值
			function f () {
				return ['hello', 'world', 'my', 'name', 'is Lilei'];
			}
			let [hello, world,, ...who] = f()  // 兩個逗號之間的值被忽略了
			console.log(hello) => hello
			console.log(world) => world
			console.log(who) => ['name', 'is Lilei']

2. 對象解構
		2.1 基本解構
			let obj = {
				hello: 'hello',
				world: 'world'
			}
			let {hello, world} = obj
			console.log(hello) => hello
			console.log(world) => world
		
		2.2 屬性重命名
			let obj = {
				hello: 'hello',
				world: 'world'
			}
			let {hello: one, world: two} = obj;
			console.log(one) => 'hello'
			console.log(two) => 'world'

		2.3 默認值
			let obj = {
				hello: 'hello'
			}
			let {hello, world = 'world'} = obj
			console.log(hello) => hello
			console.log(world) => world
			
		2.4 重命名與默認值同時存在
			let obj = {
				hello: 'hello'
			}
			let {hello: one, world：two = 'world'} = obj
			console.log(one) => hello
			console.log(two) => world

		2.5 爲函數參數設置默認值
			function f ({name='Tim', hi={hello: 'hello', world: 'world'}, age: 18} = {}) {
				console.log(name + ':' + hi + ':' + age)
			}
			f({
				name: 'Tom',
				age: 20
			})
	
		2.6 對象展開運算符
			let obj = {
				hello: 'hello',
				world: 'world',
				name: 'Tim',
				age: 18
			}
			let {hello, world, ...hi} = obj;
			console.log(hello) => hello
			console.log(world) => world
			console.log(hi) => {name: 'Tim', age: 18}

補充說明：
        for 、 for of 、 for each 可以用來遍歷數組進行解構賦值
        for in 可以用來遍歷對象屬性進行解構賦值
        重命名現象僅能使用於對象解構賦值，因爲數組不存在名稱