Backport Basilisk internal userscripts

browser/internaluserscripts/bundled-scripts/intl-relativetimeformat-formattoparts-polyfill.user.js

@@ -0,0 +1,85 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+// ==UserScript==
+// @name         Intl.RelativeTimeFormat formatToParts Polyfill
+// @namespace    internal-userscripts
+// @description  Adds formatToParts() to native Intl.RelativeTimeFormat implementations that lack it.
+// @match        *://*/*
+// @grant        none
+// @run-at       document-start
+// ==/UserScript==
+(function () {
+  "use strict";
+
+  if (
+    typeof Intl !== "object" ||
+    typeof Intl.RelativeTimeFormat !== "function" ||
+    typeof Intl.RelativeTimeFormat.prototype.formatToParts === "function"
+  ) {
+    return;
+  }
+
+  function formatToParts(value, unit) {
+    var number = Number(value);
+    var formatted = this.format(number, unit);
+    var canonicalUnit = String(unit).replace(/s$/, "");
+    var resolved = this.resolvedOptions();
+    var numberOptions = {
+      maximumFractionDigits: 3,
+    };
+
+    if (resolved.numberingSystem) {
+      numberOptions.numberingSystem = resolved.numberingSystem;
+    }
+
+    var numberFormat = new Intl.NumberFormat(resolved.locale, numberOptions);
+    var numberParts;
+    if (typeof numberFormat.formatToParts === "function") {
+      numberParts = numberFormat.formatToParts(Math.abs(number));
+    } else {
+      numberParts = [
+        { type: "integer", value: numberFormat.format(Math.abs(number)) },
+      ];
+    }
+
+    var numberText = numberParts
+      .map(function (part) {
+        return part.value;
+      })
+      .join("");
+    var numberIndex = formatted.indexOf(numberText);
+
+    // numeric: "auto" may produce a word such as "yesterday" with no number.
+    if (numberIndex === -1) {
+      return [{ type: "literal", value: formatted }];
+    }
+
+    var parts = [];
+    if (numberIndex > 0) {
+      parts.push({ type: "literal", value: formatted.slice(0, numberIndex) });
+    }
+    numberParts.forEach(function (part) {
+      parts.push({ type: part.type, value: part.value, unit: canonicalUnit });
+    });
+    if (numberIndex + numberText.length < formatted.length) {
+      parts.push({
+        type: "literal",
+        value: formatted.slice(numberIndex + numberText.length),
+      });
+    }
+    return parts;
+  }
+
+  Object.defineProperty(
+    Intl.RelativeTimeFormat.prototype,
+    "formatToParts",
+    {
+      configurable: true,
+      writable: true,
+      value: formatToParts,
+    },
+  );
+
+  window.__internalUserscriptsIntlRelativeTimeFormatFormatToPartsPolyfill = true;
+})();