Объяснение числовых разделителей JavaScript

// How many zeroes is that? Millions? Billions? Trillions?
const msInOneYear = 31536000000;
// Is this 4,200 or 42.00 (in cents)?
const price = 4200;

// Ok, this is approximately 31.5 billion
const msInOneYear = 31_536_000_000;
// Based on the separator, this should be 42.00 (cents)
const price = 42_00;