From 0e923aa4b4a0f3c9d0ee356c03c18e443d454ba1 Mon Sep 17 00:00:00 2001
From: Caleb Fontenot <foley2431@gmail.com>
Date: Sun, 30 Apr 2023 18:33:24 -0500
Subject: [PATCH] Let's try mozilla's fixedCharAt function

---
 commands/drawDesign.cjs | 37 +++++++++++++++++++++++++++++++++++--
 1 file changed, 35 insertions(+), 2 deletions(-)

diff --git a/commands/drawDesign.cjs b/commands/drawDesign.cjs
index ba61542..d8d7417 100644
--- a/commands/drawDesign.cjs
+++ b/commands/drawDesign.cjs
@@ -262,14 +262,14 @@ function design5(input) {
 
 				if (dist > radius - 1 && dist < radius + 1) { //&& dist > radius - 1
 					lineHasInput = true;
-					outputLine += "​" + input.charCodeAt(charIterate(input)); //zero-width space
+					outputLine += "​" + input.fixedCharAt(charIterate(input)); //zero-width space
 				} else {
 					outputLine += " ";
 				}
 			}
 		} else {
 			lineHasInput = true;
-			outputLine += input.charCodeAt(charIterate(input)) + space + input + space + spaceOffset + input.charCodeAt(charIterate(input));
+			outputLine += input.fixedCharAt(charIterate(input)) + space + input + space + spaceOffset + input.fixedCharAt(charIterate(input));
 		}
 
 		//console.log(i, j, outputLine);
@@ -280,5 +280,38 @@ function design5(input) {
 	}
 	return outputString;
 }
+
+// Code from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/charAt
+
+function fixedCharAt(str, idx) {
+	str = String(str);
+  
+	const surrogatePairs = /[\uD800-\uDBFF][\uDC00-\uDFFF]/g;
+	while (surrogatePairs.exec(str) !== null) {
+	  const lastIdx = surrogatePairs.lastIndex;
+	  if (lastIdx - 2 < idx) {
+		idx++;
+	  } else {
+		break;
+	  }
+	}
+  
+	if (idx >= str.length || idx < 0) {
+	  return "";
+	}
+  
+	let ret = str.charAt(idx);
+  
+	if (
+	  /[\uD800-\uDBFF]/.test(ret) &&
+	  /[\uDC00-\uDFFF]/.test(str.charAt(idx + 1))
+	) {
+	  // Go one further, since one of the "characters" is part of a surrogate pair
+	  ret += str.charAt(idx + 1);
+	}
+	return ret;
+  }
+  
+
 //console.log(design4("super long test string super long test string"));
 //"super long test string super long test string"
\ No newline at end of file