Enable TypeScript support when running k6 via docker

[wingy3181]

Brief summary

K6_COMPATIBILITY_MODE=experimental_enhanced doesn't seem to work when running k6 through docker

Did not see any docs with regards to not working via docker at https://grafana.com/docs/k6/latest/using-k6/javascript-typescript-compatibility-mode/

k6 version

0.56.0

OS

macOS 12

Docker version and image (if applicable)

Docker version 27.4.0, build bde2b89

Steps to reproduce the problem

import { sleep } from "k6";
import http from "k6/http";
import type { Options } from "k6/options";

export const options: Options = {
  vus: 10,
  duration: "30s"
};

export default function () {
  http.get("https://test.k6.io");
  sleep(1);
}

docker run --rm -i -e K6_COMPATIBILITY_MODE=experimental_enhanced grafana/k6 run --verbose - <script.ts

Looking at the source, I think it's because it looks at the filename suffix and because it is piped into the docker container, i am assuming there is no filename?
See

k6/js/compiler/compiler.go

Line 122 in 540b433

if ps.compatibilityMode == lib.CompatibilityModeExperimentalEnhanced && strings.HasSuffix(filename, ".ts") {

Expected behaviour

To strip the types with esbuild and run the script

OR if not possible update the docs to mention this

Actual behaviour

Outputs

         /\      Grafana   /‾‾/  
    /\  /  \     |\  __   /  /   
   /  \/    \    | |/ /  /   ‾‾\ 
  /          \   |   (  |  (‾)  |
 / __________ \  |_|\_\  \_____/ 

time="2025-01-20T01:02:28Z" level=debug msg="Logger format: TEXT"
time="2025-01-20T01:02:28Z" level=debug msg="k6 version: v0.56.0 (commit/50afb99947, go1.23.4, linux/arm64)"
time="2025-01-20T01:02:28Z" level=debug msg="Resolving and reading test '-'..."
time="2025-01-20T01:02:28Z" level=debug msg="'-' resolved to 'file:///-' and successfully loaded 244 bytes!"
time="2025-01-20T01:02:28Z" level=debug msg="Gathering k6 runtime options..."
time="2025-01-20T01:02:28Z" level=debug msg="Initializing k6 runner for '-' (file:///-)..."
time="2025-01-20T01:02:28Z" level=debug msg="Detecting test type for..." test_path="file:///-"
time="2025-01-20T01:02:28Z" level=debug msg="Trying to load as a JS test..." test_path="file:///-"
time="2025-01-20T01:02:28Z" level=debug msg="Everything has finished, exiting k6 with an error!" error="could not initialize '-': could not load JS test 'file:///-': GoError: file:///-: Line 3:30 Unexpected string (and 1 more errors)\n"
time="2025-01-20T01:02:28Z" level=error msg="GoError: file:///-: Line 3:30 Unexpected string (and 1 more errors)\n" hint="script exception"