denoland · crowlKats · Feb 5, 2026 · Feb 5, 2026 · kt3k · Feb 6, 2026
@@ -0,0 +1,174 @@
+// Copyright 2018-2026 the Deno authors. MIT license.
+
+const encoder = new TextEncoder();
+const decoder = new TextDecoder();
+
+const LF = "\n".charCodeAt(0);
+const CR = "\r".charCodeAt(0);
+const BS = "\b".charCodeAt(0);
+const DEL = 0x7f;
+
+/**
+ * Represents a possible value for the confirm prompt.
+ *
+ * @typeParam T The type of the value returned when this option is selected.
+ */
+export interface PromptConfirmValue<T> {
+  /** The key the user types to select this option (e.g., "y", "n", "m"). */
+  key: string;
+  /** The display label shown in the prompt (e.g., "yes", "no", "maybe"). */
+  label?: string;
+  /** The value returned when this option is selected. */
+  value: T;
+}
+
+/** Options for {@linkcode promptConfirm}. */
+export interface PromptConfirmOptions {
+  /**
+   * The key of the default value when the user presses Enter without typing.
+   *
+   * @default {"n"}
+   */
+  default?: string;
+
+  /** Clear the current line after the user's input. */
+  clear?: boolean;
+}
+
+/** Default values for the confirm prompt. */
+export const YES_NO_VALUES: PromptConfirmValue<boolean>[] = [
+  { key: "y", value: true },
+  { key: "n", value: false },
+];
+
+/**
+ * Shows the given message and waits for the user's input. Returns the value
+ * associated with the user's selection.
+ *
+ * The prompt shows the available options with the default option's key capitalized.
+ * For example: `Continue? [y/N]` where `N` is capitalized to indicate the default.
+ * If a label is provided, it's shown in parentheses: `[y (yes)/N (no)]`.
+ *
+ * The user can type either the key or the full label to select an option.
+ *
+ * @typeParam T The type of values that can be returned.
+ * @param message The prompt message to show to the user.
+ * @param values The possible values for the prompt.
+ * @param options The options for the prompt.
+ * @returns The value of the selected option, or `null` if stdin is not a TTY.
+ *
+ * @example Basic usage with YES_NO_VALUES
+ * ```ts ignore
+ * import { promptConfirm, YES_NO_VALUES } from "@std/cli/unstable-confirm";
+ *
+ * const shouldProceed = promptConfirm("Continue?", YES_NO_VALUES);
+ * if (shouldProceed) {
+ *   console.log("Continuing...");
+ * }
+ * // Displays: Continue? [y/N]
+ * ```
+ *
+ * @example With default set to yes
+ * ```ts ignore
+ * import { promptConfirm, YES_NO_VALUES } from "@std/cli/unstable-confirm";
+ *
+ * const shouldProceed = promptConfirm("Continue?", YES_NO_VALUES, { default: "y" });
+ * // Displays: Continue? [Y/n]
+ * ```
+ *
+ * @example Custom values with labels
+ * ```ts ignore
+ * import { promptConfirm } from "@std/cli/unstable-confirm";
+ *
+ * const result = promptConfirm("Save changes?", [
+ *   { key: "y", label: "yes", value: "save" },
+ *   { key: "n", label: "no", value: "discard" },
+ *   { key: "c", label: "cancel", value: "cancel" },
+ * ], { default: "c" });
+ * // Displays: Save changes? [y (yes)/n (no)/C (cancel)]
+ * ```
+ *
+ * @example With clear option
+ * ```ts ignore
+ * import { promptConfirm, YES_NO_VALUES } from "@std/cli/unstable-confirm";
+ *
+ * const shouldProceed = promptConfirm("Delete file?", YES_NO_VALUES, { clear: true });
+ * ```
+ */
+export function promptConfirm<T>(
+  message: string,
+  values: PromptConfirmValue<T>[],
+  options: PromptConfirmOptions = {},
+): T | null {
+  const input = Deno.stdin;
+  const output = Deno.stdout;
+
+  if (!input.isTerminal()) {
+    return null;
+  }
+
+  const defaultKey = options.default ?? "n";
+  const { clear } = options;
+
+  const defaultOption = values.find((v) =>
+    v.key.toLowerCase() === defaultKey.toLowerCase()
+  );
+
+  const optionsDisplay = values.map((v) => {
+    const isDefault = v.key.toLowerCase() === defaultKey.toLowerCase();
+    const key = isDefault ? v.key.toUpperCase() : v.key.toLowerCase();
+    return `${key}${v.label ? ` (${v.label})` : ""}`;
+  }).join("/");
+
+  const prompt = `${message} [${optionsDisplay}] `;
+  output.writeSync(encoder.encode(prompt));
+
+  input.setRaw(true);
+  try {
+    const answer = readLineFromStdinSync();
+    const trimmedAnswer = answer.trim().toLowerCase();
+
+    if (trimmedAnswer === "") {
+      return defaultOption?.value ?? values[0]!.value;
+    }
+
+    const selectedOption = values.find((v) =>
+      v.key.toLowerCase() === trimmedAnswer ||
+      v.label?.toLowerCase() === trimmedAnswer
+    );
+
+    if (selectedOption) {
+      return selectedOption.value;
+    }
+
+    return defaultOption?.value ?? values[0]!.value;
+  } finally {
+    if (clear) {
+      output.writeSync(encoder.encode("\r\x1b[K"));
+    } else {
+      output.writeSync(encoder.encode("\n"));
+    }
+    input.setRaw(false);
+  }
+}
+
+function readLineFromStdinSync(): string {
+  const c = new Uint8Array(1);
+  const buf: number[] = [];
+
+  while (true) {
+    const n = Deno.stdin.readSync(c);
+    if (n === null || n === 0) {
+      break;
+    }
+    if (c[0] === CR || c[0] === LF) {
+      break;
+    }
+    if (c[0] === BS || c[0] === DEL) {
+      buf.pop();
+    } else {
+      buf.push(c[0]!);
+    }
+  }
+  return decoder.decode(new Uint8Array(buf));
+}