is-html-tag-opening

Does an HTML tag start at given position?

Install

This package is pure ESM. If you're not ready yet, install an older version of this program, 2.1.0 (npm i is-html-tag-opening@2.1.0).

npm i is-html-tag-opening

Quick Take

import { strict as assert } from "assert";

import { isOpening } from "is-html-tag-opening";

const text = "<span>a < b<span>";

// opening span tag's opening
assert.equal(isOpening(text, 0), true);

// unencoded bracket between a and b
assert.equal(isOpening(text, 8), false);

// closing span tag's opening
assert.equal(isOpening(text, 11), true);

Documentation

Please visit codsen.com for a full description of the API.

Contributing

To report bugs or request features or assistance, raise an issue on GitHub.

Licence

MIT License.

Copyright © 2010-2025 Roy Revelt and other contributors.

Change Log

All notable changes to this project will be documented in this file. See Conventional Commits for commit guidelines.

4.0.0 (2022-12-01)

BREAKING CHANGES

• Minimum supported Node version is v14.18; we're dropping v12 support

3.1.0 (2022-08-12)

Features

• export types (dd81890)
• export types (11b5fb9)

3.0.15 (2022-04-18)

Fixed

• tweak types (6e721d2)

3.0.0 (2021-09-09)

Features

• migrate to ES Modules (8c9d95d)

BREAKING CHANGES

• programs now are in ES Modules and won't work with Common JS require()

2.1.0 (2021-05-24)

Features

• config file based major bump blacklisting (e15f9bb)

2.0.15 (2021-04-11)

Reverts

• Revert "chore: setup refresh" (23cf206)

2.0.9 (2021-03-23)

Fixed

• address the opts.allowCustomTagNames in context of malformed closing tags (0a785fa)
• better detection of missing opening bracket when slash + known tag name follows (b569953)

2.0.1 (2021-01-28)

Fixed

• add testStats to npmignore (f3c84e9)

2.0.0 (2021-01-23)

Features

• rewrite in TS, start using named exports (7842225)

BREAKING CHANGES

• previously, you'd consume like: import isOpening from ... - now import { isOpening } from ...

1.10.1 (2020-12-15)

Performance Improvements

• improve from 1.91 opts/sec to 186.179 opts/sec in one branch (eadc8ee)

1.10.0 (2020-12-13)

Features

• improve the broken tag recognition, set up more exhaustive tests (811a166), closes #1

1.9.0 (2020-11-28)

Accidental version bump during migration to SourceHut. Sorry about that.

1.8.0 (2020-09-07)

Features

• add type checks and split tests into multiple files (6a40e8b)

1.7.0 (2020-03-16)

Fixed

• require that tag name would not be followed by equal sign (9081082)

Features

• add more tests and finally fix the dashes in front of tag names (2a36483)
• make the requirements more strict for when opening bracket is missing (a672d99)
• opts.skipOpeningBracket (6238e92)
• require that tag names matched if !opts.allowCustomTagNames (0638865)
• require that tag names would not start with a dash (messes up broken comment tag logic) (e0ff061)

1.6.0 (2020-02-09)

Features

• opts.allowCustomTagNames (1771e43)

1.5.0 (2019-12-27)

Features

• recognise tags that have attributes with no quotes (cfe677c)

1.4.0 (2019-12-21)

Features

• recognise unknown html attributes with dashes (d13d043)

1.3.0 (2019-12-14)

Features

• add one more type of char arrangement - slash in front, confirmed tag name follows (8d1ecc9)

1.2.0 (2019-11-18)

Features

• improve the algorithm to include way more broken tag cases (fd94b61)
• loosen the requirements for the character that follows recognised tag name sequence (6201e2b)

1.1.0 (2019-11-02)

Features

• init (04dfb3b)
• recognise any html tags which start with bracket followed by a known tag name (3ac6327)

1.0.0 (2019-11-01)

• First public release