How to destructure an object's property and property's properties. ES6 Javascript

问题

I have an object

const complicatedObject = {
  propertyA: {
    property1: 1,
    property2: 2
  },
  propertyB: {
    property1: 1,
    property2: 2
  }
}

If I want to grab propertyA I do

const { propertyA } = complicatedObject 

console.log(propertyA) // { property1: 1, property2: 2}

If I want to grab propertyA's property1 value I do

const { propertyA: { property1 } } = complicatedObject

console.log(property1) // 1

I can grab propertyA and propertyA's property1 this way.

const { 
  propertyA, 
  propertyA: { 
    property1 
  } 
} = complicatedObject

console.log(propertyA) // { property1: 1, property2: 2}
console.log(property1) // 1

Is there a simpler way to get both propertyA and property1?

I read the following but I felt like nothing jumped out to me as being the answer.

https://hacks.mozilla.org/2015/05/es6-in-depth-destructuring/
http://exploringjs.com/es6/ch_destructuring.html#sec_more-obj-destructuring

Thanks!

回答1:

Just use two separate destructuring statements like so:

const { propertyA } = complicatedObject; 
const { property1 } = propertyA;

Demonstration:

const complicatedObject = {
  propertyA: {
    property1: 1,
    property2: 2
  },
  propertyB: {
    property1: 1,
    property2: 2
  }
}
const { propertyA } = complicatedObject;
const { property1 } = propertyA;

console.log(propertyA);
console.log(property1);

However, if you want to use the most concise code possible, and just wanted property1's value (1), you could use this method instead:

const { propertyA: { property1 } } = complicatedObject;

Demonstration:

const complicatedObject = {
    propertyA: {
        property1: 1,
        property2: 2
    },
    propertyB: {
        property1: 1,
        property2: 2
    }
}
const { propertyA: { property1 } } = complicatedObject;
console.log(property1);

Hopefully this helps!

回答2:

This is the correct way:

const { 
  propertyA, 
  propertyA: { 
    property1 
  } 
} = complicatedObject

If you want to access both propertyA and property1 without using multiple declaration.

console.log(propertyA) // { property1: 1, property2: 2}
console.log(property1) // 1

But if I were you, I would do just like:

const { propertyA } = complicatedObject
console.log(propertyA)
console.log(propertyA.property1)

Or, using multiple declaration:

const { propertyA } = complicatedObject,
      { property1 } = propertyA
console.log(propertyA, property1)

Actually, the purpose of your post is to question to use like:

const { propertyA: { property1 } } = complicatedObject
console.log(propertyA, property1)

And I would say, this is not possible. Because, constructuring object with colon just behaves an alias to the property. For eg.

const { propertyA: A } = complicatedObject
console.log(A) // works as if it is propertyA
console.log(propertyA) // won't work because propertyA is transformed to A

In similar,

const { propertyA: { property1 } } = complicatedObject

propertyA is transformed to { property1 } and can be accessed property1.

Also an alias to property1,

const { propertyA: { property1: prop1 } } = complicatedObject
console.log(prop1)

来源：https://stackoverflow.com/questions/53893095/how-to-destructure-an-objects-property-and-propertys-properties-es6-javascrip

标签

javascript

arrays

object

ecmascript-6

destructuring