deno_cliwrap

Convenient wrapper for launching CLI applications in Deno.

Module link: https://deno.land/x/cliwrap

Usage

In the following examples, we’ll use deno executable as it’s safe to assume you’re familiar with it and you have it already installed.

Detect deno executable version

We’ll call deno -V and capture standard output.

import {
  Cli,
  createPipeTargetToDelegate,
} from "https://deno.land/x/cliwrap/mod.ts";

let stdout = "";
const cmd = Cli.wrap("deno")
  .withArguments(["-V"])
  .withStandardOutputPipe(
    createPipeTargetToDelegate((data) => {
      stdout += data.text;
      if (data.eol) {
        stdout += "\r\n";
      }
    })
  )
  .execute();

await cmd.waitForExit();
console.log(stdout); // deno 1.23.2

Evaluate any code in Deno runtime

We’ll call deno run -, where ‘-’ means that script will be read from stdin.

import {
  Cli,
  createPipeSourceFromString,
  createPipeTargetToDelegate,
} from "https://deno.land/x/cliwrap/mod.ts";

const fnText = `console.log('Hello World'.replace('o', ''));`;

let stdout = "";
const cmd = Cli.wrap("deno")
  .withArguments(["run", "-"])
  .withStandardInputPipe(createPipeSourceFromString(fnText))
  .withStandardOutputPipe(
    createPipeTargetToDelegate((data) => {
      stdout += data.text;
      if (data.eol) {
        stdout += "\r\n";
      }
    })
  )
  .execute();

const cmdResult = await cmd.waitForExit();

console.log(cmdResult.code); // 0 - success
console.log(stdout); // "Hell World"

Capture stderr

We’ll call deno run but with a script that contains syntax error. Our goal is to capture error message.

import {
  Cli,
  CommandResultValidation,
  createPipeSourceFromString,
  createPipeTargetToDelegate,
} from "https://deno.land/x/cliwrap/mod.ts";

const fnText = `console.log('Hello World'.eplace('o', ''));`;

let stderr = "";
const cmd = Cli.wrap("deno")
  .withArguments(["run", "-"])
  .withStandardInputPipe(createPipeSourceFromString(fnText))
  .withStandardErrorPipe(
    createPipeTargetToDelegate((data) => {
      stderr += data.text;
      if (data.eol) {
        stderr += "\r\n";
      }
    })
  )
  .withValidation(CommandResultValidation.None) // Required to prevent throwing Error
  .execute();

const cmdResult = await cmd.waitForExit();

console.log(cmdResult.code); // 1 - error
console.log(stderr); // error: Uncaught TypeError: "Hello World".eplace is not a function