/** Let's define an object with two properties*/
const desktop = {CPU: "Intel",Memory: "16GB"
};/** Let's define a property at runtime. * This property we'll set as non-enumerable.*/
Object.defineProperty(desktop, 'Operating_System', {value: "Windows 10",enumerable: false
});/* Let's try to iterate through the properties of the desktop object.* Expected: "CPU" "Memory"The property desktop won't appear as we iterate because the enumerable property is set to false.*/ for( let keys in desktop){console.log(keys);
}//Same as using Object.keys() methods
console.log(Object.keys(desktop));

这是上面的示例代码的步骤。

Object.assign(target, ...sources)

第一个参数是目标对象。简而言之，该target对象将是不同来源相结合的结果。

/*
* In this example, let's declare two objects, in our example, food and clothes.
* After that, let's try to merge the two objects into one.*///declare two objects
const food = { color: 'blue'};
const clothes = { brand: 'Guess'};
//merge two objects
const result = Object.assign({ companyName: "XYZ" }, food, clothes);//The output would be:{companyName: "XYZ", color: "blue", brand: "Guess"}
console.log(result); 

克隆对象

/** In this example, let's declare one object and clone it into an empty object. *///declare an object
const customer = { fName: 'Jin', lName: 'Necesario', handsome: true };
//clone the customer object
const clonedCustomer = Object.assign({}, customer);//The output would be: {fName: "Jin", lName: "Necesario", handsome: true}
console.log(clonedCustomer);

关于Object.assign()方法的注意事项

function Person(first, last, age, eyecolor) {this.firstName = first;this.lastName = last;this.age = age;this.eyeColor = eyecolor;
}const newPerson = new Person("jin", 'necesario', 100, 'brown');Person.prototype.nationality = "English";/*
* Person {firstName: "jin", lastName: "necesario", age: 100, eyeColor: "brown"}
* age: 100
* eyeColor: "brown"
* firstName: "jin"
* lastName: "necesario"
* __proto__:
* nationality: "English"
* constructor: ƒ Person(first, last, age, eyecolor)
* __proto__: Object
*/
console.log(newPerson);/*output english*/
console.log(newPerson.nationality);
console.log(newPerson.__proto__.nationality);let result = Object.assign({}, newPerson);console.log(result);/*undefined because no access to [[proto]]*/
console.log(result.nationality);
console.log(result.__proto__.nationality);

它不会复制getter和setter。

const customer = {fName: 'Jin',lName: 'Necesario',get fullName() {return this.lName + " " +  this.fName;},set fullName(value){const parts = value.split(" ");this.fName = parts[0];this.lName = parts[1];}
};let result = Object.assign({}, customer);/*
* We are showing that this object has a getter and setter that will be
* available in the target object
* {enumerable: true, configurable: true, get: ƒ, set: ƒ}
*   configurable: true
*   enumerable: true
*   get: ƒ fullName()
*   set: ƒ fullName(value)
*   __proto__: Object
*/console.log(Object.getOwnPropertyDescriptor(customer,'fullName'));/** Output: * { fName: "Jin", lName: "Necesario", fullName: "Necesario, Jin"}*/
console.log(result);/*
* Output:
* {value: "Necesario, Jin", writable: true, enumerable: true, configurable: true}
*  configurable: true
*  enumerable: true
*  value: "Necesario, Jin"
*  writable: true
*  __proto__: Object
*/
console.log(Object.getOwnPropertyDescriptor(result,'fullName'));

$.extend和Object.assign()之间的区别？

let customer = {id: 1,details: {firstName: 'Jin',lastName: 'Necesario',tall: true}
};let customer2 = {id: 2,details: {firstName: 'Vincent'}
};let newCustomer = Object.assign({}, customer, customer2);
let newCustomer2 = $.extend(true, {}, customer, customer2);/*** output:* {details: {firstName: "Vincent"}id: 2}*/
console.log(newCustomer);/***  output:*  {*    details: {firstName: "Vincent", lastName: "Necesario", tall: true}*    id: 2*   }*/
console.log(newCustomer2); 

总结