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React ES6 Destructuring


Destructuring

To illustrate destructuring, we'll make a sandwich. Do you take everything out of the refrigerator to make your sandwich? No, you only take out the items you would like to use on your sandwich.

Destructuring is exactly the same. We may have an array or object that we are working with, but we only need some of the items contained in these.

Destructuring makes it easy to extract only what is needed.


Destructing Arrays

Here is the old way of assigning array items to a variable:

Before:

const vehicles = ['mustang', 'f-150', 'expedition'];

// old way
const car = vehicles[0];
const truck = vehicles[1];
const suv = vehicles[2];

Here is the new way of assigning array items to a variable:

With destructuring:

const vehicles = ['mustang', 'f-150', 'expedition'];

const [car, truck, suv] = vehicles;

When destructuring arrays, the order that variables are declared is important.

If we only want the car and suv we can simply leave out the truck but keep the comma:

const vehicles = ['mustang', 'f-150', 'expedition'];

const [car,, suv] = vehicles;

Destructuring comes in handy when a function returns an array:

Example

function calculate(a, b) {
  const add = a + b;
  const subtract = a - b;
  const multiply = a * b;
  const divide = a / b;

  return [add, subtract, multiply, divide];
}

const [add, subtract, multiply, divide] = calculate(4, 7);

Try it Yourself »


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Destructuring Objects

Here is the old way of using an object inside a function:

Before:

const vehicleOne = {
  brand: 'Ford',
  model: 'Mustang',
  type: 'car',
  year: 2021, 
  color: 'red'
}

myVehicle(vehicleOne);

// old way
function myVehicle(vehicle) {
  const message = 'My ' + vehicle.type + ' is a ' + vehicle.color + ' ' + vehicle.brand + ' ' + vehicle.model + '.';
}

Here is the new way of using an object inside a function:

With destructuring:

const vehicleOne = {
  brand: 'Ford',
  model: 'Mustang',
  type: 'car',
  year: 2021, 
  color: 'red'
}

myVehicle(vehicleOne);

function myVehicle({type, color, brand, model}) {
  const message = 'My ' + type + ' is a ' + color + ' ' + brand + ' ' + model + '.';
}

Try it Yourself »

Notice that the object properties do not have to be declared in a specific order.

We can even destructure deeply nested objects by referencing the nested object then using a colon and curly braces to again destructure the items needed from the nested object:

Example

const vehicleOne = {
  brand: 'Ford',
  model: 'Mustang',
  type: 'car',
  year: 2021, 
  color: 'red',
  registration: {
    city: 'Houston',
    state: 'Texas',
    country: 'USA'
  }
}

myVehicle(vehicleOne)

function myVehicle({ model, registration: { state } }) {
  const message = 'My ' + model + ' is registered in ' + state + '.';
}

Try it Yourself »


Test Yourself With Exercises

Exercise:

Use destructuring to extract only the third item from the array, into a variable named suv.

const vehicles = ['mustang', 'f-150', 'expedition'];

const [] = vehicles;

Start the Exercise