duration-str

Tiny, zero-dependency utility for formatting seconds into time strings and parsing them back, with full support for custom templates.

Perfect for timers, media players, logs, and UI displays.

Install

npm install duration-str

Quick Example

import { timeFromSeconds, secondsFromTime } from 'duration-str';

timeFromSeconds(5053);
// → "01:24:13"

secondsFromTime("01:24:13");
// → 5053

Why this library?

✅ Bidirectional — format and parse durations

✅ Custom templates with round-trip safety

✅ Zero dependencies

✅ Small & predictable

✅ TypeScript support with full type definitions

❌ No Moment / Day.js overhead

Custom Formats (Round-Trip Safe)

Format seconds using your own template:

const output_template = (h, m, s) => `${h}H ${m}M ${s}S`;

const str = timeFromSeconds(5053, { output_template });
// "01H 24M 13S"

Parse it back using a matching template string:

secondsFromTime("01H 24M 13S", {
  template_string: "{H}H {M}M {S}S"
});
// → 5053

API

timeFromSeconds(seconds, options?)

Formats a number of seconds into a string.

Parameters

• seconds — number

Options

• hours_padding — number (default: 2)
• minutes_padding — number (default: 2)
• seconds_padding — number (default: 2)
• seconds_decimal_places — number (default: 0)
• decimal_symbol — string (default: ".")
• output_template — (hours, minutes, seconds) => string (Note: parameters are strings)

secondsFromTime(timeString, options?)

Parses a formatted time string back into seconds.

Parameters

• timeString — string

Options

• decimal_symbol — string (default: ".")
• template_string — string (default: "{H}:{M}:{S}")

License

MIT