TypeScript 解构和展开

解构数组

let input = [1, 2];

let [first, second] = input;

console.log(first,second);

[first, second] = [second, first];

function f([first, second]: [number, number]){

    console.log(first,second);

}

f([1,2]);

let [first, ...rest] = [1,2,3,4];

console.log(first,rest);

let [first] = [1,2,3,4];

console.log(first);

let [, second, , fourth] = [1,2,3,4];

console.log(second,fourth);

let tuple: [number, string, boolean] = [7, "hello", true];

let [a, b, c] = tuple;

let [a, ...bc] = tuple;

let [a,b,c, ...d] = tuple;

let [a] = tuple;

let [, b] = tuple;

let o = {

    a: "foo",

    b: 12,

    c: "bar"

}

let {a, b} = o;

({a, b} = {a:"baz",b:101});

let {a, ...passthrough} = o;

let total = passthrough.b + passthrough.c.length;

let {a:newName1, b:newName2} = o;

let {a, b}: {a:string, b:number} = o;

function keepWholeObject(wholeObject: {a:string, b?:number}){

    let {a,b = 1001} = wholeObject;

}

type C = {a:string, b?: number}

function f({a,b}: C): void{

}

function f({ a="", b = 0} = {} ): void{

}

f();

function f({a,b = 0 } = {a: "" }): void {

}

let first = [1, 2];

let second = [3, 4];

let bothPlus = [0, ...first, ...second, 5];

let defaults = {food: "spicy" ,price : "$$" , ambiance: "noisy" };

let search = {...defaults, food: "rich" };

class C {

    p = 12;

    m() {

    }

}

let c = new C();

let clone = {...c};

clone.p;

clone.m(); // error!