beautifier/js-beautify

Beautification problem with JS Single Line Comment <!--

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#1,835 opened on Aug 31, 2020

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 (9 comments) (0 reactions) (1 assignee)JavaScript (8,342 stars) (1,460 forks)batch import
good first issuelanguage: javascripttype: bug

Description

In Javascript <!-- is treated as a single-line comment just like //.

js-beautify works as expected when the line starts with <!--:

Input: <!--alert(1)commented

Output: <!--alert(1)commented

Otherwise it will break the syntax:

Input: alert(1)<!--commented

Output: alert(1) < !--commented

Contributor guide

Tech stack
javascript
Domain
tooling
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 understanding of JavaScript parsing
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50
Research direction
Investigate the tokenizer or comment handling in js beautify, likely in files like 'js/index.js' or 'core/tokenizer.js'. The issue occurs when `<! ` is not at the start of a line, so the regex or logic that identifies single line comments might need to be extended to include `<! ` as a comment starter. Look at how `//` is handled and add similar handling for `<! `. Check existing tests for comment handling and write a failing test for this case.