Extract a valid heading level (1 - 6) from a tag name
headingLevel('h1'); //=> 1
headingLevel('H6'); //=> 6
headingLevel('h0'); //=> null
headingLevel('h7'); //=> null
headingLevel('div'); //=> null
// ... <h1 id='blog-title'></h1> ...
const elm = document.getElementById('blog-title');
headingLevel(elm.tagName); //=> 1
npm install heading-level
bower install heading-level
Download the script file directly.
Return: Number
(1 - 6) or null
It returns a Number
of heading level, when the argument is a heading tag name, 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
.
const result = [];
for(let i = 0; i <= 7; i++) {
result.push(headingLevel('h' + i));
}
result; //=> [null, 1, 2, 3, 4, 5, 6, null]
const foo = document.createElement('h1');
const bar = document.createElement('div');
headingLevel(foo.tagName); //=> 1
headingLevel(bar.tagName); //=> null
Copyright (c) 2014 Shinnosuke Watanabe
Licensed under the MIT License.