Photo by Mohammad Rahmani on Unsplash
物件函式
| 變數 | 說明 |
|---|---|
| Object.keys() | 物件所有鍵值 |
| Object.values() | 物件所有數值 |
| Object.entries() | 把物件轉為陣列 |
| Object.fromEntries() | 把陣列轉為物件 |
| Object.assign() | 複製物件 |
| Object.hasOwnProperty() | 是否是物件本身的屬性 |
| Object.gerOwnPropertyDescriptors() | 得到這個物件內容值的一些屬性 |
| Object.setPrototypeOf() | 設定物件原型 |
| Object.getPrototypeOf() | 取的物件原型 |
Object.entries 把物件轉為陣列
const Employee = {
name: 'KJ',
age: 17
}
// [ [ 'name', 'KJ' ], [ 'age', 17 ] ]
console.log(Object.entries(Employee))
Object.gerOwnPropertyDescriptors 得到這個物件內容值的一些屬性
const Employee = {
name: 'KJ',
age: 17,
sayHi : () => {
console.log(`Hi`)
}
}
// {
// name: { value: 'KJ', writable: true, enumerable: true, configurable: true },
// age: { value: 17, writable: true, enumerable: true, configurable: true },
// sayHi: {
// value: [Function: sayHi],
// writable: true,
// enumerable: true,
// configurable: true
// }
// }
console.log(Object.getOwnPropertyDescriptors(Employee));
assign 複製物件
const target = { a: 1, b: 2 };
const source = { b: 4, c: 5 };
const returnedTarget = Object.assign(target, source);
console.log(target);
// expected output: Object { a: 1, b: 4, c: 5 }
console.log(returnedTarget);
// expected output: Object { a: 1, b: 4, c: 5 }
使用 Object.assign 複製物件
const Employee = {
name: 'KJ',
age: 17,
sayHi : () => {
console.log(`Hi`)
}
};
// 使用 Object.assign 複製物件
NewEmployee = Object.assign({}, Employee);
NewEmployee.name = 'Kay';
NewEmployee.age = 19;
// { name: 'KJ', age: 17, sayHi: [Function: sayHi] }
console.log(Employee);
// { name: 'Kay', age: 19, sayHi: [Function: sayHi] }
console.log(NewEmployee);
使用運算元 ... 合併物件
let person = {
name: 'KJ',
age: 17,
};
let job = {
jobTitle: 'Software Engineer',
location: 'Taiwan'
};
let employee = {
...person,
...job
};
console.log(employee);
// {
// name: 'KJ',
// age: 17,
// jobTitle: 'Software Engineer',
// location: 'Taiwan'
// }
後來的物件資料會覆蓋前面的物件資料
let person = {
name: 'KJ',
age: 17,
jobTitle: 'No Job',
};
let job = {
jobTitle: 'Software Engineer',
location: 'Taiwan'
};
let employee = {
...person,
...job
};
console.log(employee);
// {
// name: 'KJ',
// age: 17,
// jobTitle: 'Software Engineer',
// location: 'Taiwan'
// }
取得物件指定鍵值並宣告為變數
let person = {
name: 'KJ',
age: 17,
jobTitle: 'No Job',
};
// KJ, 17
const { name, age } = person;
取得物件指定鍵值並重新命名宣告的變數
let person = {
name: 'KJ',
age: 17,
jobTitle: 'No Job',
};
// KJ, 17
const {
name: kj_name,
age: kj_age
} = person;
Reference
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