detect-is-it-html-or-xhtml

Answers, is the string input string more an HTML or XHTML (or neither)

Table of Contents

• Install
• Purpose
• API
• Under the hood
• Contributing
• Licence

Install

npm i detect-is-it-html-or-xhtml

// consume using a CommonJS require:
const detect = require("detect-is-it-html-or-xhtml");
// or as a native ES Module:
import detect from "detect-is-it-html-or-xhtml";
// then, pass it a string containing HTML:
console.log(
  detect(
    '<img src="some.jpg" width="zzz" height="zzz" border="0" style="display:block;" alt="zzz"/>'
  )
);
// => 'xhtml'

Here's what you'll get:

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Purpose

As you know, XHTML is slightly different from HTML: HTML (4 and 5) does not close the <img> and other single tags, while XHTML does. There are more to that, but that's the major thing from developer's perspective.

When I was working on the email-comb, I was parsing the HTML and rendering it back. Upon this rendering-back stage, I had to identify, is the source code of the HTML-type, or XHTML, because I had to instruct the renderer to close all the single tags (or not close them). Ignoring this setting would have nasty consequences because, roughly, in only half of the cases my library would produce the correct code.

I couldn't find any library that analyses the code, telling is it HTML or XHTML. That's how detect-is-it-html-or-xhtml was born.

Feed the string into this library. If it's more of an HTML, it will output a string "html". If it's more of an XHTML, it will output a string xhtml. If your code doesn't contain any tags, or it does, but there is no doctype, and it's impossible to distinguish between the two, it will output null.

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API

detect(
  htmlAsString // Some code in string format. Or some other string.
);
// => 'html'|'xhtml'|null

API - Input

If the input is not String type, this package will throw an error. If the input is missing completely, it will return null.

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API - Output

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Under the hood

The algorithm is the following:

1. Look for doctype. If recognised, Bob's your uncle, here's your answer.
2. IF there's no doctype or it's messed up beyond recognition, DO scan all singleton tags (<img>, <br> and <hr>) and see which type the majority is (closed or not closed).
3. In a rare case when there is an equal amount of both closed and unclosed tags, lean for html.
4. If (there are no tags in the input) OR (there are no doctype tags and no singleton tags), return null.

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Contributing

• If you see an error, raise an issue.
• If you want a new feature but can't code it up yourself, also raise an issue. Let's discuss it.
• If you tried to use this package, but something didn't work out, also raise an issue. We'll try to help.
• If you want to contribute some code, fork the monorepo via BitBucket, then write code, then file a pull request via BitBucket. We'll merge it in and release.

In monorepo, npm libraries are located in packages/ folder. Inside, the source code is located either in src/ folder (normal npm library) or in the root, cli.js (if it's a command line application).

The npm script "dev", the "dev": "rollup -c --dev --silent" builds the development version retaining all console.logs with row numbers. It's handy to have js-row-num-cli installed globally so you can automatically update the row numbers on all console.logs.

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Licence

MIT License

Copyright (c) 2015-2019 Roy Revelt and other contributors