toggle comments with ctrl+slash

codetab.ts

@@ -83,6 +83,33 @@ const state = {
 		this.setSelection(Math.min(anchor, focus) + text.length);
 		this.startSnapping();
 	},
+	toggleComment() {
+		const lines = this.code.split("\n");
+		const {focusX, focusY, anchorX, anchorY} = this;
+		const lineInSelection = (i: number) => i >= Math.min(focusY, anchorY) && i <= Math.max(focusY, anchorY);
+		const allLinesAreCommented = lines.every((line, i) => {
+			if (lineInSelection(i) && !line.trim().startsWith("// ")) {
+				return false;
+			} else {
+				return true;
+			}
+		});
+		const newLines = lines.map((line, i) => {
+			if (lineInSelection(i)) {
+				if (allLinesAreCommented) {
+					return line.slice(3);
+				} else {
+					return "// "+line;
+				}
+			} else {
+				return line;
+			}
+		});
+		this.code = newLines.join("\n");
+		const shiftBy = allLinesAreCommented ? -3 : 3;
+		this.setSelection({x: anchorX+shiftBy, y: anchorY}, {x: focusX+shiftBy, y: focusY});
+		this.startSnapping();
+	},
 	indent(indentString: string) {
 		const lines = this.code.split("\n");
 		const {focusX, focusY, anchorX, anchorY} = this;
@@ -494,6 +521,9 @@ const update = async () => {
 	if (keyPressed("Y") && ctrlKeyDown()) {
 		state.redo();
 	}
+	if (keyPressed("/") && ctrlKeyDown()) {
+		state.toggleComment();
+	}
 }
 
 const draw = () => {