The 7 most transformative JavaScript features from ES10

JavaScript has come a long way in the past 10 years with brand new feature upgrades in each one.

Still remember when we created classes like this?

function Car(make, model) { this.make = make; this.model = model; } // And had to join strings like this = function() { console.log("Vroom! This " + this.make + " " + this.model + " is driving!"); };

Yeah, a lot has changed!

Let’s take a look at the 7 most significant features that arrived in ES10 (2019); and see the ones you missed.

1. Modularization on the fly: Dynamic imports

The ES10 year was the awesome year when import could now act as function, like require(). An async function.

Keeping imports at the top-level was no longer a must; We could now easily resolve the module’s name at compile time.

Loading modules optionally and only when absolutely needed for high-flying performance…

async function asyncFunc() { if (condition) { const giganticModule = await import('./gigantic-module'); } }

Loading modules based on user or variable input…

import minimist from 'minimist'; const argv = minimist(process.argv.slice(2)); viewModule(; async function viewModule(name) { const module = await import(name); console.log(Object.keys(module)); }

It’s also great for using ES modules that no longer support require():

// ❌ require() of ES modules is not supported const chalk = require('chalk'); console.log('Coding Beauty')); (async () => { // ✅ Runs successfully const chalk = (await import('chalk')).default; console.log('Coding Beauty')); })();

2. Flattening the curve

flat() and flatMap() gave much cleaner ways to easily flatten multidimensional arrays.

Eradicating the need for painful array-looping flattening code:

const colorSwatches = [ 'cream🟡', ['scarlet🔴', 'cherry🔴'], ['blue🔷', ['sky blue🟦', 'navy blue🔵']], ]; // Default depth of 1 console.log(colorSwatches.flat()); // ['cream🟡', 'scarlet🔴', 'cherry🔴', 'blue🔷', // ['sky blue🟦', 'navy blue🔵']] console.log(colorSwatches.flat(2)); // ['cream🟡', 'scarlet🔴', 'cherry🔴', 'blue🔷', // 'sky blue🟦', 'navy blue🔵']

flatMap() is as good as calling map(), then flat(1):

const colorSwatches = [ 'cream🟡', ['scarlet🔴', 'cherry🔴'], ['blue🔷', ['sky blue🟦', 'navy blue🔵']], ]; // map to get only the emoji console.log( colorSwatches.flatMap((color) => Array.isArray(color) ? color : color.slice(-2) ) ); // [ '🟡', 'cherry🔴', 'blue🔷', [ 'sky blue🟦', 'navy blue🔵' ] ]

3. Transform arrays to objects

ES10 was also when Object.fromEntries() arrived on the JavaScript scene.

Quickly convert list of key-value pairs to equivalent key-value object:

const entries = [ ['name', 'The Flash⚡'], ['realName', 'Barry Allen'], ['lightningColor', 'yellow🟡'], ['suitColor', 'red🔴'], ]; console.log(Object.fromEntries(entries)); /** { name: 'The Flash⚡', realName: 'Barry Allen', lightningColor: 'yellow🟡', suitColor: 'red🔴' } */

4. Clean up your strings with precisions

trimStart() and trimEnd().

Before now everyone was using trim from NPM – Happily adding 3.35KB to the project…

Even now:

But slowly losing popularity to .trim().

Then Array trim() came along, then trimStart() and trimEnd().

const fruits = ' pineapple🍍 '; console.log(fruits.trimStart()); // 'pineapple🍍 ' console.log(fruits.trimEnd()); // ' pineapple🍍' console.log(fruits.trim()); // 'pineapple🍍'

5. Catching errors without the baggage

With the new optional catch binding, you now safely omit the catch block’s error argument when you had nothing to do with it:

// ❌ Before ES10 try { iMayExplodeAnyMomentNow(); } catch (err) { // Or else error } // ✅ try { iMayExplodeAnyMomentNow(); } catch {}

6. Sorting without surprise

Stable Array sort.

Previously when sorting an array there was absolutely no way we could guarantee the arrangement of the equal elements.

But in the post-ES10 JS code here, we are 100% sure that react always comes before vue always comes before angular.

const geniusPortfolio = [ { tool: 'javascript', years: 2000, }, { tool: 'react', years: 1000 }, { tool: 'vue', years: 1000 }, { tool: 'angular', years: 1000 }, { tool: 'assembly', years: 7000 }, ]; const sortedDesc = geniusPortfolio.sort((a, b) => { return b.years - a.years; }); const sortedAsc = geniusPortfolio.sort((a, b) => { return a.years - b.years; });

7. Go big or go home: BigInts

The name BigInt gives it purpose away: For loading up on unbelievably humongous integer values:

const bigInt = 240389470239846028947208942742089724204872042n; const bigInt2 = BigInt( '34028974029641089471947861048917649816048962' ); console.log(typeof bigInt); console.log(bigInt); console.log(typeof bigInt2); console.log(bigInt2); console.log(bigInt * bigInt2);

Because normal integers can’t:

// ✖️ Stored as double const normalInt = 240389470239846028947208942742089724204872042; const normalInt2 = 34028974029641089471947861048917649816048962; console.log(typeof normalInt); console.log(normalInt); console.log(typeof normalInt2); console.log(normalInt2); // ✖️ Precision lost console.log(normalInt * normalInt2);

Final thoughts

ES10 marked a significant leap forward for JavaScript with several features that have become essential for modern development.

Use them write cleaner code with greater conciseness, expressiveness, and clarity.

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