Show caret, backspace, and left-right arrows

repl.ts

@@ -1,8 +1,9 @@
 import faux from "./builtins.ts";
-import { getKeysPressed, shiftKeyDown, shiftMap } from "./keyboard.ts";
+import { getKeysPressed, shiftKeyDown, shiftMap, K } from "./keyboard.ts";
 import { font } from "./font.ts";
 
 let line = "";
+let index = 0;
 
 const update = () => {
 	for (const key of getKeysPressed()) {
@@ -15,13 +16,31 @@ const update = () => {
 			}
 		}
 		if (char in font) {
-			line += char;
+			line = line.slice(0, index)+char+line.slice(index);
+			index += 1;
+		} else if (key === K.BACKSPACE) {
+			line = line.slice(0, -1);
+			index -= 1;
+			if (index < 0) {
+				index = 0;
+			}
+		} else if (key === K.ARROW_LEFT) {
+			index -= 1;
+			if (index < 0) {
+				index = 0;
+			}
+		} else if (key === K.ARROW_RIGHT) {
+			index += 1;
+			if (index > line.length) {
+				index = line.length;
+			}
 		}
 	}
 }
 
 const draw = () => {
 	faux.clear_screen();
+	faux.draw_rect((2+index)*4, 0, 5, 6, 3);
 	faux.draw_text(0, 0, "> "+line);
 }