#formatting code explainers

typescript

type CurrencyFormatOptions = {
  locale?: string;
  currency: string;
  showDecimals?: boolean;

Caching Intl.NumberFormat for currency

memoization internationalization caching

Intermediate 9 steps

javascript

const UNITS = ['B', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB'];
 
export function formatBytes(bytes, { decimals = 1, binary = false } = {}) {
  if (!Number.isFinite(bytes)) {

Formatting byte counts into human units

logarithms formatting default-parameters

Intermediate 8 steps

rust

use std::fmt;
 
#[derive(Clone, Copy, PartialEq, Eq)]
pub struct Money {

Formatting money with Rust's Display trait

trait-implementation integer-arithmetic enums

Intermediate 10 steps

ruby

require "time"
require "tzinfo"
 
module TimeConverter

Converting timestamps across time zones with TZInfo

timezones iso8601 parsing

Intermediate 8 steps

java

import java.time.Instant;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;

Converting timestamps across time zones in Java

date-time time-zones instant

Intermediate 6 steps

ruby

module DurationFormatter
  UNITS = [
    ['week', 604_800],
    ['day', 86_400],

Turning seconds into human-readable durations in Ruby

greedy-decomposition modular-arithmetic formatting

Intermediate 7 steps

go

package geometry
 
import "fmt"

Implementing fmt.Stringer in Go

interfaces stringer composition

Beginner 5 steps