Path operations

Many applications need to manipulate file paths in one way or another. The Deno standard library provides simple utilities for this.

First we will import the module from the Deno standard library

import * as path from "jsr:@std/path";

Converting from a file url to a directory can be done simply by the `fromFileUrl` method from the appropriate implementation.

const p1 = path.posix.fromFileUrl("file:///home/foo");
const p2 = path.win32.fromFileUrl("file:///home/foo");
console.log(`Path 1: ${p1} Path 2: ${p2}`);

We can also choose to not specify and automatically use whatever Deno is running on

const p3 = path.fromFileUrl("file:///home/foo");
console.log(`Path on current OS: ${p3}`);

We can get the last part of a file path using the basename method

const p = path.basename("./deno/is/awesome/mod.ts");
console.log(p); // mod.ts

We can get the directory of a file path using the dirname method

const base = path.dirname("./deno/is/awesome/mod.ts");
console.log(base); // ./deno/is/awesome

We can get the extension of a file path using the extname method

const ext = path.extname("./deno/is/awesome/mod.ts");
console.log(ext); // .ts

We can format a path using a FormatInputPathObject

const formatPath = path.format({
  root: "/",
  dir: "/home/user/dir",
  ext: ".html",
  name: "index",
});
console.log(formatPath); // "/home/user/dir/index.html"

When we want to make our code cross-platform, we can use the join method. This joins any number of string by the OS-specific file separator. On Mac OS this would be foo/bar. On windows, this would be foo\bar.

const joinPath = path.join("foo", "bar");
console.log(joinPath);

We can get the current working directory using the built-in cwd method

const current = Deno.cwd();
console.log(current);

Run this example locally using the Deno CLI:

deno run --allow-read https://examples.deno.land/path-operations.ts

Additional resources:

Checking for file existence Streaming File Operations