Multiple ways of merging objects in javaScript

Various ways javaScript combines objects:

1. Method 1: Object.assign(obj1, obj2, …)

Parameter 1: obj1 is the target object
Parameter 2: obj2 is the source object

Note: between objects, the attribute with the same name will be overwritten by the attribute value of the object behind

const obj1 = {
    
    
	a: 1,
	b: 2,
}
const obj2 = {
    
    
	b: 3,
	c: 4,
}
const result = Object.assign(obj1, obj2)
console.log(result) // {a: 1, b: 3, c: 4}

2. Method 2: es6 new syntax, expansion operator... [Three points]

{...obj1, ...obj2}
Note: between objects, the attributes with the same name will be overwritten by the attribute values ​​of the following objects

const obj1 = {
    
    
	a: 1,
	b: 2,
}
const obj2 = {
    
    
	b: 3,
	c: 4,
}
const result = {
    
    ...obj1, ...obj2}  // 返回一个新的对象。
console.log(result) // {a: 1, b: 3, c: 4}

// 顺带一提， 数组之间的合并，也可以使用 扩展运算符 .
// 如： [...arr1, ...arr2]

Knowledge expansion:

The spread operator... [Three points] can also be used for merging between arrays.

The difference is:
the arrays will only be merged, even if they are the same value, they will not be overwritten. (This is where it differs from objects.)

let arr1 = [1,2,4]

let arr2 = [4,5,6]

let arr3 = [...arr1, ...arr2]

console.log(arr3)  // [1, 2, 4, 4, 5, 6]  

Summary: 0.0