Browser Support

Espalier targets the latest two major versions of each evergreen browser. The library ships modern JavaScript and CSS with no transpilation or vendor-prefixed fallbacks.

Minimum Browser Versions

The table below lists the effective floor for each browser, determined by the most demanding platform feature Espalier uses.

If your users are on a managed browser policy (common in enterprise and government environments), these are the versions to enforce.

What Sets the Floor

The highest bar is CSS Nesting (Chrome 120) and Relative Color Syntax (Firefox 128, Safari 18). Both reached Baseline status in late 2024.

Required Polyfills

Espalier does not bundle polyfills. When a standard is not yet universally available, the consuming application is responsible for loading the polyfill. This keeps the library dependency-free and lets you drop the polyfill the moment your browser matrix no longer needs it.

Temporal API

Required for: <esp-date-picker>, <esp-input input-type="date">

The Temporal API provides date and time types. Espalier expects it on globalThis.Temporal. If a supported browser does not provide it, install the polyfill before loading Espalier:

npm install @js-temporal/polyfill

import { Temporal } from "@js-temporal/polyfill";
globalThis.Temporal ??= Temporal;

await import("@taprootio/espalier");

Or via CDN in your document <head>:

<script src="https://cdn.jsdelivr.net/npm/@js-temporal/polyfill/dist/index.umd.js"></script>
<script>
  globalThis.Temporal ??= temporal.Temporal;
</script>

Without the polyfill, <esp-date-picker> renders an inline error message instead of the calendar UI.

Not Supported

Support Policy

Espalier ships modern JavaScript and CSS without a transpilation layer or built-in compatibility shims. Load polyfills in your application when needed, and remove them when your browser matrix supports the feature natively.

For detailed rationale and per-feature breakdowns, see the Caveats guide.