HMR update doing nothing

[mischnic]

Here's a github repo with a super simple node web app using TypeScript that reproduces the issue:
https://github.com/programmist/parcel-hmr-issue-repro

I created this project by initializing TS and Node projects in a new directory...

mkdir hello-web
cd hello-web
tsc --init
npm init -y

...and then adding an index.html file which references index.ts. The TS file adds text to an empty <h1> element when it is loaded.

To Reproduce the Issue:

(Using Parcel 2.9.3)

• Clone this repo, cd into the parcel-hmr-issue-repro directory, and run npx parcel index.html
• Open http://localhost:1234 in your browser
• You should see a page with an <h1> element containing the text "Hello World"
• With the Parcel server still running, change title.textContent in index.ts to something different and save the file.

At this point I would have expected to see the text on the page update, but it doesn't. All I see is a "console was cleared" message in the JS console. In order to see an update I must manually refresh the browser page.

Incidentally, I went to the line of code which clears the console and set a breakpoint a few lines earlier in the onmessage handler, just below where the HMRMessage is being parsed. Then I made another update to my index.ts file. When inspecting the data, I can see the TS changes I made in data.assets[0].output.

Originally posted by @programmist in #6685 (comment)

[mischnic]

The problem is that for some reason, the env hashes don't match up in this line

parcel/packages/runtimes/hmr/src/loaders/hmr-runtime.js

Line 143 in 3027926

let assets = data.assets.filter(asset => asset.envHash === HMR_ENV_HASH);

causing the updated JS asset to be filtered out and not be applied.