Deno functions

In place of the Node standard lib, you can use this built-in methods on the Deno module. No imports need.

Available when using deno run index.ts or the interactive console deno repl.

Deno.cwd
Deno.copyFile
Deno.readAllSync

See more with:

$ deno repl

> Object.keys(Deno).sort()
...

Standard library

Updating

You might have to rebuild your standard library modules when upgrading Deno.

$ cd ~
$ deno upgrade
$ deno cache --reload

It is also recommend to reference standard library modules by locked versions - this means they will always be available and get installed regardless of Deno version.

Resources

Modules

From Unix cat example in the docs.

  • Deno.args accesses the command line arguments.
  • Deno.open is used to get a handle to a file.
  • Deno.copy is used to transfer data from the file to the output stream.

From the docs, use the fs module from the standard library:

  • main.ts 
      import { copy } from "https://deno.land/std@0.87.0/fs/copy.ts";

  copy("log.txt", "log-old.txt");

$ deno run --allow-read --allow-write main.ts

See Read and write text files.

Summarized below.

Deno.readTextFile("./people.json");

Deno.writeTextFile("./hello.txt", "Hello World!");