Discussion on: A simple way to replace npm scripts in Deno

[Heiker]

Looks really good. I see that it can run a selected file with the permissions, but what about random commands? Is there a plan for that?

[Ryan]

I was able to use the code from this article and the denox package to create a similar npm feel. If you pass your script in as a string then split the script on the spaces to get your arguments it becomes much more usable.

If Khaled added a logical check on the config file to check if a file or script is being provided I'm sure we could achieve the desired outcome.

async function exec(script: String): Promise<any> {
  const args = script.split(' ');
  const proc = await Deno.run({ cmd: args }).status();

  if(proc.success == false) {
    Deno.exit(proc.code);
  }

  return proc;
}

export default exec;

[Ryan]

github.com/BentoumiTech/denox/pull/15 I took the liberty to add the functionality you're looking for. Denox is a pretty awesome package so hopefully, this gets picked up.

[Heiker]

That's awesome. But I'm a little bit worried by this right here: const args = script.split(' ');, it doesn't handle quoted arguments. If you give it something like this

some-cli-tool -m "a message" -m "some other message"

You would get.

["some-cli-tool" "-m", "\"a", "message\"", "-m", "\"some", "other", "message\"" ]

Would Deno.run handle that?

[Ryan]

That's a great observation. Do you have any suggestions on how to handle this case?

[Heiker]

I found this package: exec. It does the same thing as that function with more options. You could use that. It only handles double quotes but it's an improvement.

If anyone is curious how they do it, here it is.

function splitCommand(command) {
  var myRegexp = /[^\s"]+|"([^"]*)"/gi;
  var splits = [];

  do {
    //Each call to exec returns the next regex match as an array
    var match = myRegexp.exec(command);
    if (match != null) {
      //Index 1 in the array is the captured group if it exists
      //Index 0 is the matched text, which we use if no captured group exists
      splits.push(match[1] ? match[1] : match[0]);
    }
  } while (match != null);

  return splits;
}

[Ryan]

What about double quotes enclosed within single quotes, echo 'And he said: "My name is!" ${name}'. It's a contrived example but you get the gist.

[Heiker]

For that you would get.

[ "echo", "'And", "he", "said:", "My name is!", "aa'" ]

See, the double quotes stayed, but everything else is broken. Having a bulletproof regex is a real pain. If you want to improve it, you have to modify this var myRegexp = /[^\s"]+|"([^"]*)"/gi;.