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•Created by Codex on 4/22/2025 in #questions

Use `swc_ecma_compat_es2017::async_to_generator` for conditional async transformations

Hey team, I've been working on a plugin that takes async functions and transforms them to generators for usage with mobx flows. I've gotten reasonably far but came across: https://docs.rs/swc_ecma_compat_es2017/latest/src/swc_ecma_compat_es2017/async_to_generator.rs.html#39-46 This transformation is exactly what i've been aiming for and would make for a far more robust solution, as what i've written so far handles the conditional cases as I expect. The issue i'm running into is that I'd like to instantiate the AsyncToGenerator visitor to visit_children_with it when the conditions are met to perform this transformation, but async_to_generator returns Pass which does not satisfy VisitMut Would it be reasonable to export a function that does work this way from swc_ecma_compat_es2017? Or am I down the wrong path here?

4 replies

CDCloudflare Developers

•Created by Codex on 6/20/2024 in #workers-help

K6 load testing and 429s

Hey team Currently been working on load testing a simple worker (just a JS 10 liner kind of deal) we have (non-free/ent tier) and have found that when trying to perform load testing using K6 we begin to see a flood of 429's I did find this post: https://community.cloudflare.com/t/can-requests-to-workers-get-rate-limited/435598/2 Which suggests i'm encountering on paid it defends against a small amount of IPs sending too many requests But I cannot seem to find a ways to configure either whitelisting the IP's i'm using or to temporarily disable this throttling feature. Where can I find more information about this? Is there configuration I can see either on the worker level or in the portal around this?

13 replies

SCSWC Community

•Created by Codex on 12/11/2023 in #questions

Folder import resulting in undefined

Having a tonne of trouble with trying to get swc working with jest as doing a folder import results in an empty object:

import * as x from '..';

import * as x from '..';

{__esModule: true}

{__esModule: true}

swcrc:

{
  "$schema": "http://json.schemastore.org/swcrc",
  "jsc": {
    "parser": {
      "syntax": "typescript",
      "tsx": true
    },
    "transform": {
      "react": {
        "runtime": "automatic"
      }
    },
    "experimental": {
      "plugins": [
        [
          "@swc/plugin-emotion",
          {
            "autoLabel": "always"
          }
        ]
      ]
    }
  }
}

{
  "$schema": "http://json.schemastore.org/swcrc",
  "jsc": {
    "parser": {
      "syntax": "typescript",
      "tsx": true
    },
    "transform": {
      "react": {
        "runtime": "automatic"
      }
    },
    "experimental": {
      "plugins": [
        [
          "@swc/plugin-emotion",
          {
            "autoLabel": "always"
          }
        ]
      ]
    }
  }
}

tsconfig:

{
  "compilerOptions": {
    "target": "es2022",
    "module": "esnext",
    "composite": true,
    "incremental": true,
    "noEmit": true,
    "pretty": true,
    "sourceMap": true,

    "lib": ["dom", "dom.iterable", "esnext"],

    "strict": true,

    "allowSyntheticDefaultImports": true,
    "downlevelIteration": true,
    "esModuleInterop": true,
    "forceConsistentCasingInFileNames": true,
    "isolatedModules": true,
    "jsx": "react-jsx",
    "jsxImportSource": "@emotion/react",
    "moduleResolution": "node",
    "noFallthroughCasesInSwitch": true,
    "skipLibCheck": true,
    "useDefineForClassFields": true
  }
}

{
  "compilerOptions": {
    "target": "es2022",
    "module": "esnext",
    "composite": true,
    "incremental": true,
    "noEmit": true,
    "pretty": true,
    "sourceMap": true,

    "lib": ["dom", "dom.iterable", "esnext"],

    "strict": true,

    "allowSyntheticDefaultImports": true,
    "downlevelIteration": true,
    "esModuleInterop": true,
    "forceConsistentCasingInFileNames": true,
    "isolatedModules": true,
    "jsx": "react-jsx",
    "jsxImportSource": "@emotion/react",
    "moduleResolution": "node",
    "noFallthroughCasesInSwitch": true,
    "skipLibCheck": true,
    "useDefineForClassFields": true
  }
}

What am I doing wrong 🤔

1 replies

SCSWC Community

•Created by Codex on 7/6/2023 in #questions

Transforming `import.meta` with jest and swc

I've spent a few hours trying to find how this is meant to work with jest and swc. config:

{
  "jsc": {
    "parser": {
      "syntax": "typescript",
      "tsx": true,
      "decorators": true
    },
    "transform": {
      "react": {
        "runtime": "automatic",
        "importSource": "@emotion/react"
      }
    }
  },
  "isModule": true
}

{
  "jsc": {
    "parser": {
      "syntax": "typescript",
      "tsx": true,
      "decorators": true
    },
    "transform": {
      "react": {
        "runtime": "automatic",
        "importSource": "@emotion/react"
      }
    }
  },
  "isModule": true
}

Jest:

/// <reference types="node" />

const config = JSON.parse(fs.readFileSync(`${process.cwd()}/.swcrc`, 'utf-8'))
delete config.exclude
config.swcrc = false
config.jsc.transform.hidden = {
  ...config.jsc.transform.hidden,
  jest: true
}

/**
 * @type { import("jest").Config }
 */
module.exports = {
  roots: ['<rootDir>/src/', '<rootDir>/test/'],
  setupFilesAfterEnv: ['<rootDir>/src/setupTests.ts'],
  moduleFileExtensions: ['js', 'jsx', 'ts', 'tsx'],
  snapshotSerializers: ['@emotion/jest/serializer'],
  testEnvironment: 'jsdom',
  testEnvironmentOptions: { url: 'http://localhost/' },
  testRegex: '(test|spec).tsx?$',
  transform: {
    '^.+\\.(t|j)sx?$': ['@swc/jest', config]
  }
}

/// <reference types="node" />

const config = JSON.parse(fs.readFileSync(`${process.cwd()}/.swcrc`, 'utf-8'))
delete config.exclude
config.swcrc = false
config.jsc.transform.hidden = {
  ...config.jsc.transform.hidden,
  jest: true
}

/**
 * @type { import("jest").Config }
 */
module.exports = {
  roots: ['<rootDir>/src/', '<rootDir>/test/'],
  setupFilesAfterEnv: ['<rootDir>/src/setupTests.ts'],
  moduleFileExtensions: ['js', 'jsx', 'ts', 'tsx'],
  snapshotSerializers: ['@emotion/jest/serializer'],
  testEnvironment: 'jsdom',
  testEnvironmentOptions: { url: 'http://localhost/' },
  testRegex: '(test|spec).tsx?$',
  transform: {
    '^.+\\.(t|j)sx?$': ['@swc/jest', config]
  }
}

But no matter what I try, I still hit: SyntaxError: Cannot use 'import.meta' outside a module What am I doing wrong here?

4 replies

SCSWC Community

•Created by Codex on 4/10/2023 in #questions

OOM with emotion plugin?

I was looking at adopting swc with the emotion plugin in one of our repositories when I hit this:

Caused by:
    0: failed to invoke `@swc/plugin-emotion` as js transform plugin at ../../node_modules/@swc/plugin-emotion/swc_plugin_emotion.wasm
    1: RuntimeError: out of bounds memory access
    2: heap_get_oob', /Users/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/swc-0.260.1/src/plugin.rs:228:14
failed to handle: failed to invoke plugin: failed to invoke plugin on 'Some("src/components/x.tsx")'

Caused by:
    0: failed to invoke `@swc/plugin-emotion` as js transform plugin at ../../node_modules/@swc/plugin-emotion/swc_plugin_emotion.wasm
    1: RuntimeError: out of bounds memory access
    2: heap_get_oob', /Users/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/swc-0.260.1/src/plugin.rs:228:14
failed to handle: failed to invoke plugin: failed to invoke plugin on 'Some("src/components/x.tsx")'

35 replies

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