Introduction

Suppose we have a task to create an object with dynamic key value pairs. We would start with writing some logic to achieve it. But if we are aware of a feature name computed property of ES6, our life is sorted :P

Let's start with this....

What is an object?

Let us consider a real life scenario.
A car is an object. A car has properties like weight,color, height, width, etc.

Objects are like variables which can contain many values.
Like:

var obj = {};
OR
var car = {type:"Fiat", model:"500", color:"white"};

The values are written as name:value pairs (name and value separated by a colon).

Accessing Object Properties

You can access object properties in two ways:
objectName.propertyName
OR
objectName["propertyName"]

Now, we can get to dynamic properties

var key = 'DYNAMIC_KEY',
    obj = {
        [key]: 'ES6!'
    };

console.log(obj);
// > { 'DYNAMIC_KEY': 'ES6!' }

Suppose we have a task of creating an object from an array. We will have to create key value pairs.

Consider an array like:

const personsList = ["Alan", "Smith", "Kelly", "Jason", "Nicole"];

Now to create an object out of this array with key value pairs, we can use computed property feature available in ES6 as below:

let personsObject = {};  //create an object

//Iterate over the personsList array
personsList.forEach((currentItem, index) => {
    personsObject[index] = currentItem;
});
console.log(personsObject);

// > {0: "Alan", 1: "Smith", 2: "Kelly", 3: "Jason", 4: "Nicole"}

As you can see now we have an object with dynamic key-value pairs. You can give custom key name instead of index.

For example:

personsList.forEach((currentItem, index) => {
    // personsObject[index] = currentItem;
    personsObject["name"] = currentItem;
});
console.log(personsObject);

// > {name: "Alan", name: "Smith", name: "Kelly", name: "Jason", name: "Nicole"}

Hope this helps you in some way.
Cheers !!!