From d4cb5b0f45a95f37f92cac2bb4dc8a998c31d224 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sat, 16 Jan 2021 15:40:11 +0000
Subject: Include strings for scalar values

---
 js/src/index.ts | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

(limited to 'js/src')

diff --git a/js/src/index.ts b/js/src/index.ts
index 13b1f3b..1563b59 100644
--- a/js/src/index.ts
+++ b/js/src/index.ts
@@ -1,15 +1,20 @@
 import dingbats from "./dingbats";
 
-interface UnicodeScalarValue {
+export interface UnicodeScalarValue {
     codePoint: number;
+    string: string;
 }
 
 const dingbatsByDec: {[key: string]: UnicodeScalarValue} = {};
 const dingbatsByHex: {[key: string]: UnicodeScalarValue} = {};
 
+const fromCodePoint = String.fromCodePoint ? String.fromCodePoint : fromCodePointPolyfill;
+
 for (const dingbat of dingbats) {
+    const codePoint = parseInt(dingbat["Unicode dec"], 10);
     const scalarValue = {
-        codePoint: parseInt(dingbat["Unicode dec"], 10),
+        codePoint: codePoint,
+        string: fromCodePoint(codePoint),
     };
 
     dingbatsByDec[dingbat["Typeface name"] + "_" + dingbat["Dingbat dec"]] = scalarValue;
@@ -27,3 +32,16 @@ export function dec(typeface: string, dec: string): UnicodeScalarValue | undefin
 export function hex(typeface: string, hex: string): UnicodeScalarValue | undefined {
     return dingbatsByHex[typeface + "_" + hex.toUpperCase()];
 }
+
+function fromCodePointPolyfill(codePoint: number) {
+    if (codePoint <= 0xFFFF) {
+        // BMP
+        return String.fromCharCode(codePoint);
+    } else {
+        // Astral
+        // https://mathiasbynens.be/notes/javascript-encoding#surrogate-formulae
+        const highSurrogate = Math.floor((codePoint - 0x10000) / 0x400) + 0xD800;
+        const lowSurrogate = (codePoint - 0x10000) % 0x400 + 0xDC00;
+        return String.fromCharCode(highSurrogate, lowSurrogate);
+    }
+};
-- 
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