Mursal Furqan Kumbhar

Posted on May 29

Write Minimal ES6 Code

#javascript #webdev #programming #web

In the constantly-changing JavaScript ecosystem, designing simple and efficient code is more important than ever. The release of ES6 introduced a slew of new capabilities that simplify and streamline the way we write JavaScript. This article discusses various new ES6 approaches that can replace older, more verbose patterns, resulting in cleaner and more readable code. From Boolean casting to the powerful spread operator, these strategies increase code readability, efficiency, and maintainability. Let's look at some of the essential techniques that any JavaScript writer should follow to build minimum ES6 code.

1. Boolean Casting

Today's recommended method according to Airbnb's style guide

const age = Boolean(input.value) //old

const age = !!input.value //new

2. Nullish Coalescing

Returns its right-hand side when its left-hand side operand is null or undefined

//old
const addId = (user, id) => {
     user.id = 
          id !== null && id !== undefined
               ? id
               : "Unknown"
     return user
}

//new
const addId = (user, id) => {
     user.id = id ?? "Unknown"
     return user
}

3. Default Parameters

Description: Function Parameters default to undefined, so it's useful to set a value for this eventuality.

//old
const createUser = (name, email) => {
     const user = {
          email,
          name: name ?? "Unknown",
     }
     // create user
}

//new
const createUser = (
     name = "Unknown",
     email
) => {
     const user = { email, name }
     // create user
}

4. Optional Chaining

Description: Allows you to read the value of a deeply nested property without checking if it's a valid chain.

//old
const hasValidPostcode = u => 
     u &&
     u.address &&
     u.address.postcode &&
     u.address.postcode.valid

//new
const hasValidPostcode = u => u?.address?.postcode?.valid

5. Destructuring Objects

Description: Write less code by unpacking properties from objects into distinct variables.

//old
const save = params => {
     saveData(
          params.name,
          params.email,
          params.dob
     )
}

//new
const save = ({name, email, dob}) => {
     saveData(name, email, dob)
}

6. Destructuring Arrays

Description: Write less code by unpacking values from arrays into distinct variables.

//old
const data = [
     ["axios", "recharts"],
     ["flocked", "flick"]
]

const plugins = data[0], apps = data[1]

//new
const data = [
     ["axios", "recharts"],
     ["flocked", "flick"]
]

const [plugins, apps] = data

7. Spread Operator

Description: Merge two objects into one using this cool syntax, also very clean when coding objects.

//old
const details = {name: "Man Utd"}
const stats = {games: 7, points: 21}

const team = Object.assign(
     {},
     details,
     stats
)

//new
const details = {name: "Man Utd"}
const stats = {games: 7, points: 21}

const team = {
     ...details,
     ...stats
}

8. For(of)

Description: Arguably the same amount of code required but for(of) is known to be 24% faster than forEach.

//old
const array = []
const fillArray = items => {
     items.forEach(i => array.push(i))
}

//new
const array = []
const fillArray = items => {
     for (let i of items) {
          array.push(i)
     }
}

Conclusion

To summarize, using ES6 features may significantly simplify your JavaScript code, making it more brief, legible, and efficient. Integrating these current methods will result in cleaner and more maintainable code, improving both development and performance. Implement these approaches to improve your code standards and simplify your tasks.

Happy Coding 👨‍💻

Top comments (14)

Ben Sinclair • May 29

I strongly disagree with point 1. It looks way too much like optimising for code size rather than clarity, and it's completely pointless. People who care about saving 7 bytes are going to be shocked at what happens when they run their code through a minimiser, which is what's going to happen during the build, and then those people are going to be shocked at what happens when their script is gzipped and maybe even SPDYd up during transmission over https.

In point 8, I think you should default to using const for the variable. It might seem like it's being re-assigned in the for clause, but it's actually scoped to the enclosed block so defining it as const is usually the safe move.

Arnaud Dagnelies • May 29

From my experience, the usage of !! is much more common than the explicit Boolean(...) cast. Actually, I have never even seen it in practice yet. So from my POV, !! feels familiar and straightforward while the cast feels ...hmm ...very exotic.

lionel-rowe • May 31 • Edited

Really? I use explicit casts all the time as they seem so much clearer in intent. The explicit meaning of !! is "not-not", rather than "convert to boolean". Similarly for Number (or parseInt, parseFloat, etc. depending on use case) vs +... I want to convert to a number, not make the variable positive.

Artem Sapegin • May 30

Totally agree — shorter isn't always better, and we shouldn't optimize for code brevity but for code clarity. I've collected many more similar examples, though !! is probably the most harmless and commonly used of all.

lionel-rowe • May 31

Yeah, Airbnb style guide is trash. It also recommends const fn = function longAssDescriptiveName () {} over function normalFunctionName() {} 🤢

Alex Lohr • May 29 • Edited

#1 If you don't use terser or another JS minification engine, go ahead, otherwise it makes no difference whatsoever.

#5/6/7 Be aware that proxies and getters will only be called once in destructuring and spreading. If those are used e.g. to provide subscription for reactive behavior (e.g. in Solid.js), this will break your code.

#8 never use forEach like this to copy an array. Use const array = [...items] for a shallow copy to be even faster.

Otherwise, avoid premature optimisations.

Eckehard • May 29

This type of "optimization" is overestimated in most cases. Javascript does a very good job optimizing execution (with some very special exceptions like for/in), and the effort to save some bytes often does not really pay back. On the long run, good readability and a clear structure shouldn't be sacrificed just to minimize the code size.