parcel-bundler/parcel

Compile to js doesn't modify script type=application/ts to type=application/javascript

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#2267 opened on Nov 9, 2018

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:bug: Bug:heavy_check_mark: Confirmed BugGood First Issue

Description

🐛 bug report

Out of the box, the compilation to js of some ... works but in the resulting html the type attribute is kept intact (application/ts) and the browser (firefox in my case) doesn't execute the produced javascript

🎛 Configuration (.babelrc, package.json, cli command)

yarn global add parcel-bundler
yarn init -y

{
  "name": "compile-to-js",
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT",
  "devDependencies": {
    "typescript": "^3.1.6"
  }
}

🤔 Expected Behavior

The produced html should contain type="application/javascript"

😯 Current Behavior

The produced html contains type="application/ts"

💻 Code Sample

index.html:

<!doctype html>
<html>
    <body>
        <script type="application/ts">
            type TT = "bouh" | "bar"
            function log(t: TT){
                console.log(t)
            }
            log("bouh")
        </script>
    </body>
</html>

parcel index.html

Result:

<!doctype html>
<html>
    <body>
        <script type="application/ts">function log(t) {
  console.log(t);
}

log("bouh");</script>
    </body>
</html>

🌍 Your Environment

Software Version(s)
Parcel 1.10.3
Node v11.1.0
npm/Yarn 6.4.1/1.9.4
Operating System OSX

Contributor guide

Tech stack
typescriptjavascript
Domain
frontendbuild system
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic knowledge of Parcel bundlerFamiliarity with HTML script tags
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
Look into how Parcel processes HTML files and transforms script tags. The issue is likely in src/assets/HTMLAsset.js or similar file where the type attribute is updated after compilation. Check for existing logic that updates type for JavaScript but not for TypeScript. Consider adding a mapping from content type to output type, e.g., 'application/ts' > 'application/javascript'. The fix should ensure that after TypeScript compilation, the script tag's type attribute is updated to 'application/javascript'.