掌握 JavaScript 中对象和数组的展开运算符

const arr1 = [1, 2, 3];
const arr2 = [...arr1];  // spread operator to copy arr1

console.log(arr2);  // output: [1, 2, 3]

const arr1 = [1, 2, 3];
const arr2 = [4, 5, 6];

const combined = [...arr1, ...arr2];

console.log(combined);  // output: [1, 2, 3, 4, 5, 6]

const arr = [1, 2, 3];

const newarr = [0, ...arr, 4];

console.log(newarr);  // output: [0, 1, 2, 3, 4]

const person = { name: "john", age: 30 };

const personcopy = { ...person };

console.log(personcopy);  // output: { name: "john", age: 30 }

const person = { name: "john", age: 30 };
const address = { city: "new york", zip: "10001" };

const combined = { ...person, ...address };

console.log(combined);  // output: { name: "john", age: 30, city: "new york", zip: "10001" }

const person = { name: "john", age: 30 };

const updatedperson = { ...person, city: "new york" };

console.log(updatedperson);  // output: { name: "john", age: 30, city: "new york" }

const numbers = [1, 2, 3, 4];

function sum(a, b, c, d) {
  return a + b + c + d;
}

console.log(sum(...numbers));  // output: 10 (1 + 2 + 3 + 4)

const obj1 = { a: 1, b: { c: 2 } };
const obj2 = { ...obj1 };

obj2.b.c = 3;

console.log(obj1.b.c);  // output: 3 (both obj1 and obj2 share the same reference to b)
console.log(obj2.b.c);  // output: 3

const arr = [
  { id: 1, name: "john" },
  { id: 2, name: "jane" }
];

// updating the object with id 1
const updatedarr = arr.map(obj =>
  obj.id === 1 ? { ...obj, name: "jack" } : obj
);

console.log(updatedarr);  
// output: [ { id: 1, name: 'jack' }, { id: 2, name: 'jane' } ]

const newprops = { ...this.props, additionalprop: "new value" };

this.setState(prevState => ({
  ...prevState,
  user: { ...prevState.user, name: "Updated Name" }
}));