PrismJS/prism

Keep Markup: the markup is removed if it's the last element

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#1618 opened on Nov 18, 2018

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Description

I don't if this is intended or not but if the markup (in the exemple below <div class="keep"></div>") is the last element, the Keep Markup plugin will remove it:

<!DOCTYPE html>
<html>
  <head>
    <link href="prism.css" rel="stylesheet" />
    <style>
    .keep {
      height: 1rem;
      width: 1rem;
      background-color: red;
    }
    </style>
  </head>
  <body>
    <pre><code class="language-css"><div class="keep"></div>p { color: red }<div class="keep"></div></code></pre>
    <script src="prism.js"></script>
  </body>
</html>

And here's the result:

error

As you can see the first <div class="keep"></div> is preserved but the last is removed. If I add some content after the div then it's working as expected:

good

Contributor guide

Tech stack
javascript
Domain
frontend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
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 JavaScript
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
The issue is about the Keep Markup plugin in Prism. The relevant source file is 'plugins/keep markup/prism keep markup.js'. The bug occurs when the markup element is the last child. Check the logic that determines preserving markup, likely a loop or index issue. Consider adding a test case for this scenario.