How to conditionally build an object in JavaScript with ES6

by Janeth Kent Date: 09-08-2019 javascript coding ES6


The arrival of ES6 brought us, among many other news, the spread syntax, which, as you will already know, allows us to save a few lines of code and improve legibility.

Specifically, this syntax allows us to destructure the parameters that we pass to a function so that our code goes from:

function foo(data) {
const id = data.id
const title = data.name
// more...
}

to

function foo({id, title}) {
//more
}

But also thanks to the operator spread ... , we can expand (unwrap) objects in order to perform operations such as:

const obj1 = {a: 1, b: 2};
const obj2 = {...obj1, c: 3};
// obj2 = {a: 1, b: 2, c: 3};

However, another implementations of this syntax is to create objects with certain properties dependent on a condition, which is what I wanted to talk about in this article.

For example, if we have the following code:

const obj1 = {a: 1, b: 2};
if (condition) {
ob1.c = 3;
}
if (otherCondition) {
obj.d = 4;
}const obj1 = {a: 1, b: 2};
if (condition) {
ob1.c = 3;
}
if (otherCondition) {
obj.d = 4;
}

By using the spread syntax we can transform it into the following, much more readable:

const obj1 = {
a: 1, 
b: 2,
...(condition ? {c:3} : {}),
...(otherCondition ? {c:4} : {})
};

This is possible because the operator only acts if the condition is true. Remember that if you are going to use this way of creating objects, 0 evaluates to false so you should perform a strict check.

As you can see, using this operator allows us to improve our code a lot and get rid of those annoying ifs we had to add if we wanted to achieve something similar.

 
by Janeth Kent Date: 09-08-2019 javascript coding ES6 hits : 9686  
 
Janeth Kent

Janeth Kent

Licenciada en Bellas Artes y programadora por pasión. Cuando tengo un rato retoco fotos, edito vídeos y diseño cosas. El resto del tiempo escribo en MA-NO WEB DESIGN END DEVELOPMENT.

 
 
 

Related Posts

How to use the codePointAt method in JavaScript

The JavaScript codePointAt method has more or less the same function as the charCodeAt method, used to get the 16-bit Unicode representation of the character at a certain position in…

How to check if a value is a number in JavaScript

In this short tutorial we are going to look at the various methods that exist to find out if a value is a number in JavaScript.   1. Using the isNaN() function   One…

How to use the charCodeAt method in JavaScript

The charCodeAt method is accepted by strings in JavaScript, returning the 16-bit Unicode code of the character at the position we pass as a parameter to the method. The charCodeAt method…

How to use the charAt method in JavaScript

The charAt method is accepted by strings in JavaScript, returning the position of the character passed as a parameter within the string. If the string contains multiple occurrences of the character…

Strings in JavaScript: What they are and how to use them

In this tutorial we are going to explain what strings are and how they are used in JavaScript. The tutorial is intended for people who are learning to program in…

Dates in local format with Javascript

In the articles we have about dates in JavaScript we were missing one about how to create dates in local format with JavaScript. That is to say, being able to…

Formatting hours in Javascript

Continuing with the set of articles that talk about internationalisation elements, like the previous one where we talked about relative dates in JavaScript, we will see in this one how…

Request data with prompt in JavaScript

After having published several articles about how to manipulate arrays and dates, today I will publish a post that some of you will find too basic and others will find…

Relative dates in JavaScript

One of the interesting things about the internationalisation library represented in the Int object is the handling of relative dates in Javascript. This handling allows us to represent a date…

How to access webcam and grab an image using HTML5 and Javascript

We often use webcams to broadcast video in real time via our computer. This broadcast can be viewed, saved and even shared via the Internet. As a rule, we need…

The JavaScript forEach loop

We have already talked about how to handle some of loops  types in Javascript including for, for-in and for-off loops. In the case of today we are going to see how…

What are React Hooks and what problems they solve

Working with React, - and before the release of Hooks in version 16.8 -  there was always the possibility to create components in three different ways based on a number of…

We use our own and third-party cookies to improve our services, compile statistical information and analyze your browsing habits. This allows us to personalize the content we offer and to show you advertisements related to your preferences. By clicking "Accept all" you agree to the storage of cookies on your device to improve website navigation, analyse traffic and assist our marketing activities. You can also select "System Cookies Only" to accept only the cookies required for the website to function, or you can select the cookies you wish to activate by clicking on "settings".

Accept All Only sistem cookies Configuration