Strip ANSI escape sequences

References: https://todo.sr.ht/~emersion/gamja/11

lib/ansi.js

@@ -0,0 +1,53 @@
+// See https://modern.ircdocs.horse/formatting.html
+
+const BOLD = "\x02";
+const ITALIC = "\x1D";
+const UNDERLINE = "\x1F";
+const STRIKETHROUGH = "\x1E";
+const MONOSPACE = "\x11";
+const COLOR = "\x03";
+const COLOR_HEX = "\x04";
+const REVERSE_COLOR = "\x16";
+const RESET = "\x0F";
+
+function isDigit(ch) {
+	return ch >= "0" && ch <= "9";
+}
+
+export function strip(text) {
+	var out = "";
+	for (var i = 0; i < text.length; i++) {
+		var ch = text[i];
+		switch (ch) {
+		case BOLD:
+		case ITALIC:
+		case UNDERLINE:
+		case STRIKETHROUGH:
+		case MONOSPACE:
+		case REVERSE_COLOR:
+		case RESET:
+			break; // skip
+		case COLOR:
+			if (!isDigit(text[i + 1])) {
+				break;
+			}
+			i++;
+			if (isDigit(text[i + 1])) {
+				i++;
+			}
+			if (text[i + 1] == "," && isDigit(text[i + 2])) {
+				i += 2;
+				if (isDigit(text[i + 1])) {
+					i++;
+				}
+			}
+			break;
+		case COLOR_HEX:
+			i += 6;
+			break;
+		default:
+			out += ch;
+		}
+	}
+	return out;
+}