배열 및 객체의 JS 전체 복사 작업 예

let arr = [ undefined, function(){ console.log(123); }, true, null, { name:"123", age:23 } ]; // arr作为拷贝对象

let arr1 = Array.from(arr); arr[0] = 2; console.log(arr1); // [ undefined, [Function], true, null, { name: '123', age: 23 } ]

let arr1 = Object.assign([], arr) arr[0] = 2; console.log(arr1); // [ undefined, [Function], true, null, { name: '123', age: 23 } ]

let arr1 = arr.slice(0); arr[0] = 2; console.log(arr1); // [ undefined, [Function], true, null, { name: '123', age: 23 } ]

let arr1 = arr.concat(); arr[0] = 2; console.log(arr1); // [ undefined, [Function], true, null, { name: '123', age: 23 } ]

// let [...arr1] = arr; // 这两种都可以 let arr1 = [...arr]; arr[0] = 2; console.log(arr1); // [ undefined, [Function], true, null, { name: '123', age: 23 } ]

let obj = { name: "a", age: 20, sex: false, user: { a: 20, n: "b" }, f: function(){ return 1; }, u: undefined, n: null }