1808357 - Add better error message for invalid JSON importmap

Status: RESOLVED FIXED

(Core :: JavaScript Engine, enhancement, P3)

Description

[Nicolas Chevobbe [:nchevobbe]]

Steps to reproduce

1. Open a tab with data:text/html,<meta charset=utf8> <script type="importmap" >{{"imports": {"square": "./circle.js"}}</script> (note the extra { before imports)
2. Open the console

Result

The following error message appears in the console:

Uncaught SyntaxError: JSON.parse: expected property name or '}' at line 1 column 2 of the JSON data

While it's better than nothing, it could be hard to understand this relates to the importmap being invalid.

For what it's worth, Chrome prints the following:

Uncaught SyntaxError: Failed to parse import map: invalid JSON

Our Learn more link could point to https://developer.mozilla.org/en-US/docs/Web/HTML/Element/script/type/importmap (but that can be a follow up for the DevTools team)

Comment 1

[Yoshi Cheng-Hao Huang [:allstars.chh][:allstarschh][:yoshi]]

Hi Nicolas
Can you clarify "The better error message"?
IMO, our JSON parser provides more detailed information like lineno and columnno,
when the import map text is long, it would be pretty helpful.

With simply "invalid JSON", you still don't know where it went wrong.

Comment 2

[Matthew Gaudet (he/him) [:mgaudet]]

A custom error message here for the case of JSON decoding for the purpose of an ImportMap does seem like a user experience improvement -- we should keep the line and col numbers tho!

Comment 3

[Nicolas Chevobbe [:nchevobbe]]

(In reply to Yoshi Cheng-Hao Huang [:allstars.chh][:allstarschh][:yoshi] from comment #1)

Hi Nicolas
Can you clarify "The better error message"?
IMO, our JSON parser provides more detailed information like lineno and columnno,
when the import map text is long, it would be pretty helpful.

With simply "invalid JSON", you still don't know where it went wrong.

we could do something like

Uncaught SyntaxError: Failed to parse import map: invalid JSON, expected property name or '}' at line 1 column 2 of the JSON data

Comment 4

[Yoshi Cheng-Hao Huang [:allstars.chh][:allstarschh][:yoshi]]

Attachment: Bug 1808357: Add better error message for importmaps of invalid JSON format.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/05d23ba4b590
Add better error message for importmaps of invalid JSON format. r=jonco

Comment 6

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/05d23ba4b590