https://github.com/shinnn/heading-level.js

Extract a valid heading level (1 - 6) from a tag name
https://github.com/shinnn/heading-level.js

Last synced: 27 days ago
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Extract a valid heading level (1 - 6) from a tag name

• Host: GitHub
• URL: https://github.com/shinnn/heading-level.js
• Owner: shinnn
• License: mit
• Created: 2014-05-19T14:47:23.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2016-09-08T19:53:49.000Z (about 8 years ago)
• Last Synced: 2024-10-11T22:26:02.079Z (about 1 month ago)
• Language: JavaScript
• Size: 24.4 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# heading-level.js

[![NPM version](https://img.shields.io/npm/v/heading-level.svg)](https://www.npmjs.org/package/heading-level)

[![Bower version](https://img.shields.io/bower/v/heading-level.svg)](https://github.com/shinnn/heading-level.js/releases)

[![Build Status](https://travis-ci.org/shinnn/heading-level.js.svg?branch=master)](https://travis-ci.org/shinnn/heading-level.js)

[![Coverage Status](https://img.shields.io/coveralls/shinnn/heading-level.js.svg)](https://coveralls.io/r/shinnn/heading-level.js)

[![devDependency Status](https://david-dm.org/shinnn/heading-level.js/dev-status.svg)](https://david-dm.org/shinnn/heading-level.js#info=devDependencies)

Extract a valid heading level (1 - 6) from a tag name

```javascript

headingLevel('h1'); //=> 1

headingLevel('H6'); //=> 6

headingLevel('h0'); //=> null

headingLevel('h7'); //=> null

headingLevel('div'); //=> null

// ... 
 ...

const elm = document.getElementById('blog-title');

headingLevel(elm.tagName); //=> 1

```


## Installation

### Install with package manager

#### [npm](https://www.npmjs.com/)

```

npm install heading-level

```

#### [Bower](http://bower.io/) 

```

bower install heading-level

```

### Standalone

[Download the script file directly.](https://raw.githubusercontent.com/shinnn/heading-level.js/master/browser.js "view raw")

## API

### headingLevel(tagName)

Return: `Number` (1 - 6) or `null`

It returns a `Number` of heading level, when the argument is a [heading tag name](https://www.w3.org/TR/html-markup/elements.html), such as `"h3"` and `"H4"`.

It returns `null` when the argument is not a heading tag name.

It throws an error when the argument is not a `String`.

```javascript

const result = [];

for(let i = 0; i <= 7; i++) {

  result.push(headingLevel('h' + i));

}

result; //=> [null, 1, 2, 3, 4, 5, 6, null]

```

```javascript

const foo = document.createElement('h1');

const bar = document.createElement('div');

headingLevel(foo.tagName); //=> 1

headingLevel(bar.tagName); //=> null

```

## License

Copyright (c) 2014 [Shinnosuke Watanabe](https://github.com/shinnn)

Licensed under [the MIT License](./LICENSE).