Why are there _ in numbers?

Actually, this is a feature added in JavaScript in ECMAScript 2021, called “Numeric Separators,” which allows us to insert _ between numbers to enhance readability.

const readableMiliion = 1_000_000;
const regularMiliion = 1000000;
const decimal = 1_000_000.220_720;
const binary = 0b01010110_00111000;
const hexa = 0x40_76_38_6a_73;

It has been supported since Node 12.5.0, Chrome 75, Firefox 70, and Safari 13.1, so you can use it with confidence. A quick search revealed that many programming languages also support this feature.

• Numeric separators🔗