d3-time-format is a core D3 module providing robust JavaScript utilities for formatting and parsing dates and times, inspired by the venerable `strftime` and `strptime` functions from the C standard library. Currently stable at version 4.1.0, this package typically releases new major versions for significant breaking changes or feature additions, while minor and patch releases address bug fixes and smaller enhancements. It enables developers to convert `Date` objects into human-readable, locale-specific strings and vice-versa, making it indispensable for data visualization and applications requiring precise time representation. A key differentiator is its deep integration within the D3 ecosystem, frequently used alongside D3 time scales, and its comprehensive support for various format specifiers and internationalization through locale definitions, which were notably enhanced in recent versions like 4.1.0 with additional exports and updates. It explicitly adopted modern JavaScript features like `type: module` in v4 and ES2015 in v3, signaling a commitment to contemporary development practices.
npm install d3-time-formatVerified import paths — ran on the pinned version, not inferred.
This demonstrates a multi-scale time formatter, dynamically adjusting date output based on the time interval, a common pattern in D3.
Migrate your project to use ES module `import` syntax or ensure your bundler (e.g., Webpack, Rollup) is configured to handle ESM. For Node.js, ensure you are running version 12+ and using 'type: module' in your package.json or saving files as .mjs.
If supporting pre-ES2015 environments is necessary, either stick with d3-time-format 2.x or transpile your code using tools like Babel to downlevel ES2015+ syntax.
Always ensure locale data is loaded and applied using `d3.timeFormatDefaultLocale(locale)` within an asynchronous context (e.g., `await` or `.then()`) before initializing and using time formatters that depend on the custom locale.
For consistent and explicit handling of UTC dates, always use `utcFormat` and `utcParse`. If local time is desired, be aware of how different timezones and daylight saving times might affect parsing and formatting.
Change `const { timeFormat } = require('d3-time-format');` to `import { timeFormat } from 'd3-time-format';`.Ensure your project's `package.json` has `"type": "module"` if you intend to use ESM, or configure your bundler (Webpack, Rollup) to handle ESM. Alternatively, use dynamic `import()` for CJS-only environments if absolutely necessary for a v4+ package.
Double-check that the format `specifier` precisely matches the input date string. Ensure all necessary locale definitions are loaded if parsing a locale-specific string.