deno/std/fs/ensure_file.ts

// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
import * as path from "../path/mod.ts";
import { ensureDir, ensureDirSync } from "./ensure_dir.ts";
import { getFileInfoType } from "./utils.ts";
const { lstat, lstatSync, writeFile, writeFileSync } = Deno;

/**
 * Ensures that the file exists.
 * If the file that is requested to be created is in directories that do not
 * exist.
 * these directories are created. If the file already exists,
 * it is NOTMODIFIED.
 * Requires the `--allow-read` and `--alow-write` flag.
 */
export async function ensureFile(filePath: string): Promise<void> {
  try {
    // if file exists
    const stat = await lstat(filePath);
    if (!stat.isFile()) {
      throw new Error(
        `Ensure path exists, expected 'file', got '${getFileInfoType(stat)}'`
      );
    }
  } catch (err) {
    // if file not exists
    if (err instanceof Deno.errors.NotFound) {
      // ensure dir exists
      await ensureDir(path.dirname(filePath));
      // create file
      await writeFile(filePath, new Uint8Array());
      return;
    }

    throw err;
  }
}

/**
 * Ensures that the file exists.
 * If the file that is requested to be created is in directories that do not
 * exist,
 * these directories are created. If the file already exists,
 * it is NOT MODIFIED.
 * Requires the `--allow-read` and `--alow-write` flag.
 */
export function ensureFileSync(filePath: string): void {
  try {
    // if file exists
    const stat = lstatSync(filePath);
    if (!stat.isFile()) {
      throw new Error(
        `Ensure path exists, expected 'file', got '${getFileInfoType(stat)}'`
      );
    }
  } catch (err) {
    // if file not exists
    if (err instanceof Deno.errors.NotFound) {
      // ensure dir exists
      ensureDirSync(path.dirname(filePath));
      // create file
      writeFileSync(filePath, new Uint8Array());
      return;
    }
    throw err;
  }
}