developit/htm

Ampersand escapes in text content handled differently to JSX

Open

#76 opened on Mar 15, 2019

View on GitHub
 (11 comments) (5 reactions) (0 assignees)JavaScript (8,453 stars) (181 forks)batch import
discussionhelp wanted

Description

Reproduction

With the following code:

import htm from "https://unpkg.com/htm@2.1.1/dist/htm.mjs";
import { h } from "https://unpkg.com/preact@8.4.2/dist/preact.mjs";
const html = htm.bind(h);

console.log(html`<div>&lt;</div>`)

I get a VNode with .children = ["&lt;"] — i.e. what I mean to render as < gets rendered as &lt; instead.

Expected results

Testing this in JSX via say https://jsx.egoist.moe/?mode=vue, <div>&lt;</div> gets transformed into h("div", ["<"]); as I originally expected.

I haven't poked into how they are doing this… seems like something that ultimately relies on a lookup table.

Workaround

I am able to escape via string interpolation (e.g. ${'<'} instead of &lt;). Changing the last line in my sample code to:

// …

console.log(html`<div>${'<'}</div>`)

Results in a VNode with .children = ["<"] as I need. Is this the recommended style?

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
knowledge of htmunderstanding of HTML entitiesbasic JavaScript
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
The issue is about ampersand escapes not being decoded in htm's template literal processing. The fix likely requires adding a lookup table for HTML entities in the tag function. Look at the source file (likely htm.mjs) for how text content is parsed from the template strings. The current behavior escapes entities as literal text. The expected behavior is to decode them, similar to JSX. A concrete first step is to identify where the text nodes are created and add a simple entity decoding step using a mapping of common entities like &lt;, &gt;, &amp;, &quot;, etc.
Ampersand escapes in text content handled differently to JSX · developit/htm#76 | Good First Issue