How to create an empty file in Deno?

Question

As per deno documentation for writeFile if I want to write in a file and overwrite if the file already exists I need this command -

await Deno.writeFile("hello1.txt", data);  // overwrite "hello1.txt" or create it

What I need is to create an empty file and if a file with the same name already exists overwrite it with an empty file, so I tried to run the function without data and I am getting this error.

await Deno.writeFile("hello1.txt");
 An argument for 'data' was not provided.
        data: Uint8Array,

How can I create an empty file in Deno and overwrite any file exists with the same name?

Marcos Casagrande · Answer 1 · 2022-09-18T12:09:58.273

3

Pass an empty Uint8Array to Deno.writeFile

await Deno.writeFile("./hello1.txt", new Uint8Array());

You can also use Deno.open with truncate: true

await Deno.open("./hello1.txt", { create: true, write: true, truncate: true });

or Deno.create:

await Deno.create("./hello1.txt")

Alternatively, if you know the file already exists you can use Deno.truncate

await Deno.truncate("./hello1.txt");

edited Sep 18 '22 at 12:09

answered Jun 08 '20 at 10:08

Marcos Casagrande

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1

Thanks, the first option works perfectly fine, but Deno.truncate does not create an empty file, it empty an existing file. It is giving an error if the file is not already present – Puneet Singh Jun 08 '20 at 10:27
Thought you always had the file, I'll modify the answer. – Marcos Casagrande Jun 08 '20 at 10:43

score 2 · Answer 2 · edited Jun 20 '20 at 09:12

You can use Deno.create:

Creates a file if none exists or truncates an existing file and resolves to an instance of Deno.File.

await Deno.create("hello1.txt")

Process deeper file paths with possibly not existent directories safely:

import { ensureFile } from "https://deno.land/std/fs/ensure_file.ts";
const file = "./deep/hello1.txt"; // `deep` doesn't need to exist
await ensureFile(file); // ensures file and containing directories
await Deno.truncate(file);

score 1 · Answer 3 · answered Jun 08 '20 at 13:15

1

You can use writeTextFile and pass an empty string. Rest as suggested above, use ensureFile and truncate for other needs.

(async function() {
  await Deno.writeTextFile("./helloworld.txt", "")
})()

answered Jun 08 '20 at 13:15

xdeepakv

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How to create an empty file in Deno?

3 Answers3