Improve readability of numbers in your JavaScript code

Quite a common situation to have big numbers in JavaScript code e.g. during working with timestamps, intervals, timeouts, milliseconds:

// 1 minute interval
setInterval(() => {}, 60000);

// 10 sec timeout
setTimeout(() => {}, 10000);

// current time - 5 mins
const past5mins = Date.now() - 300000;

// prices
const maxPriceUsd = 100000.00;

These big numbers readability can be improved in several ways.

JavaScript Numeric Separator ( _ )

In places where it is clear that number is milliseconds and it's some common time interval e.g. 1 minute or seconds under minute or the value can be understandable quickly without additional calculation - it is possible to utilize a JavaScript Numeric Separator. So the examples above will look like this:

// 1 minute interval
setInterval(() => {}, 60_000);

// 10 sec timeout
setTimeout(() => {}, 10_000);

// prices
const maxPriceUsd = 100_000.00;

JavaScript Numeric Separators were added in ES2021 and currently supported by all modern browsers and available in Node.js v12.5.0 and later.

Move uncommon time intervals to separate lib/variable

For some cases it is better to replace big number with in-place calculation or separate constant.

For this example:

const past5mins = Date.now() - 300000;

we can improve it in next ways:

// variant 1 - in-place calculation
const past5mins = Date.now() - 5 * 60 * 1000;

// variant 2 - separate constant
const FIVE_MINS = 5 * 60 * 1000;
const past5mins = Date.now() - FIVE_MINS;