feat(menu): add back key navigation

src/menu.ts

@@ -2,11 +2,17 @@ import { BOLD, GREEN, CYAN, DIM, RESET } from "./terminal";
 
 const UP = "\x1b[A";
 const DOWN = "\x1b[B";
+const LEFT = "\x1b[D";
 const ALT_UP = "\x1bOA";
 const ALT_DOWN = "\x1bOB";
+const ALT_LEFT = "\x1bOD";
 const SPACE = " ";
 const ENTER = "\r";
 const CTRL_C = "\x03";
+const BACKSPACE = "\x7f";
+
+export const BACK = Symbol("prompt-back");
+export type PromptBack = typeof BACK;
 
 export interface Choice<T> {
   label: string;
@@ -19,6 +25,7 @@ interface BasePromptOptions {
   title: string;
   subtitle?: string;
   cancelMessage?: string;
+  allowBack?: boolean;
 }
 
 interface SinglePromptOptions<T> extends BasePromptOptions {
@@ -55,11 +62,13 @@ function padLabel(label: string, width: number) {
   return label + " ".repeat(Math.max(1, width - visibleLength(label)));
 }
 
-function controls(mode: "single" | "multi") {
+function controls(mode: "single" | "multi", showBackHint = true) {
   if (mode === "single") {
-    return `${DIM}↑/↓ navigate · enter/space select · ctrl+c cancel${RESET}`;
+    const backHint = showBackHint ? " · ←/backspace back" : "";
+    return `${DIM}↑/↓ navigate · enter/space select${backHint} · ctrl+c cancel${RESET}`;
   }
-  return `${DIM}↑/↓ navigate · space toggle · enter confirm · ctrl+c cancel${RESET}`;
+  const backHint = showBackHint ? " · ←/backspace back" : "";
+  return `${DIM}↑/↓ navigate · space toggle · enter confirm${backHint} · ctrl+c cancel${RESET}`;
 }
 
 function renderPrompt(lines: string[], previousLines: number) {
@@ -89,6 +98,9 @@ function clearPrompt(lines: number) {
 function normalizeKey(key: string, escapeBuf: string) {
   if (key === UP || key === ALT_UP) return { action: "up", escapeBuf: "" };
   if (key === DOWN || key === ALT_DOWN) return { action: "down", escapeBuf: "" };
+  if (key === LEFT || key === ALT_LEFT || key === BACKSPACE) {
+    return { action: "back", escapeBuf: "" };
+  }
   if (key === SPACE) return { action: "space", escapeBuf: "" };
   if (key === ENTER) return { action: "enter", escapeBuf: "" };
   if (key === CTRL_C) return { action: "cancel", escapeBuf: "" };
@@ -101,6 +113,9 @@ function normalizeKey(key: string, escapeBuf: string) {
     const next = escapeBuf + key;
     if (next === UP || next === ALT_UP) return { action: "up", escapeBuf: "" };
     if (next === DOWN || next === ALT_DOWN) return { action: "down", escapeBuf: "" };
+    if (next === LEFT || next === ALT_LEFT) {
+      return { action: "back", escapeBuf: "" };
+    }
     return {
       action: null,
       escapeBuf: /^[A-Za-z~]$/.test(key) || next.length > 8 ? "" : next,
@@ -126,7 +141,7 @@ function createLines<T>(
   ];
 
   if (options.subtitle) lines.push(`  ${DIM}${options.subtitle}${RESET}`);
-  lines.push(`  ${controls(mode)}`, "");
+  lines.push(`  ${controls(mode, options.allowBack !== false)}`, "");
 
   for (let i = 0; i < options.items.length; i++) {
     const item = options.items[i]!;
@@ -156,7 +171,7 @@ function ensureTTY(title: string) {
 
 export async function selectOne<T>(
   options: SinglePromptOptions<T>,
-): Promise<T | null> {
+): Promise<T | null | PromptBack> {
   ensureTTY(options.title);
 
   let cursor = 0;
@@ -178,7 +193,7 @@ export async function selectOne<T>(
   render();
 
   return new Promise((resolve) => {
-    const finish = (value: T | null) => {
+    const finish = (value: T | null | PromptBack) => {
       process.stdin.setRawMode(wasRaw === true);
       process.stdin.pause();
       process.stdin.removeListener("data", onData);
@@ -195,6 +210,9 @@ export async function selectOne<T>(
       escapeBuf = result.escapeBuf;
 
       if (result.action === "cancel") return finish(null);
+      if (result.action === "back" && options.allowBack !== false) {
+        return finish(BACK);
+      }
       if (result.action === "up" && cursor > 0) {
         cursor--;
         render();
@@ -212,7 +230,7 @@ export async function selectOne<T>(
 
 export async function selectMany<T>(
   options: MultiPromptOptions<T>,
-): Promise<T[] | null> {
+): Promise<T[] | null | PromptBack> {
   ensureTTY(options.title);
 
   const items: Choice<T | null>[] = options.selectAllLabel
@@ -267,7 +285,7 @@ export async function selectMany<T>(
   render();
 
   return new Promise((resolve) => {
-    const finish = (value: T[] | null) => {
+    const finish = (value: T[] | null | PromptBack) => {
       process.stdin.setRawMode(wasRaw === true);
       process.stdin.pause();
       process.stdin.removeListener("data", onData);
@@ -284,6 +302,9 @@ export async function selectMany<T>(
       escapeBuf = result.escapeBuf;
 
       if (result.action === "cancel") return finish(null);
+      if (result.action === "back" && options.allowBack !== false) {
+        return finish(BACK);
+      }
       if (result.action === "up" && cursor > 0) {
         cursor--;
         render();