HTML5 のカスタム属性の概要

<div id="box1" data-name="Musk"></div>
<div id="box2" data-full-name="Elon Musk"></div>

let box1 = document.getElementById('box1');
let box2 = document.getElementById('box2');
 
box1.dataset.name // Musk
box2.dataset.fullName // Elon Musk (驼峰)
 
box1.getAttribute('data-name') // Musk
box2.getAttribute('data-full-name') // Elon Musk

let box1 = document.getElementById('box1');
let box2 = document.getElementById('box2');
 
box1.dataset.name = '马斯克'
box2.setAttribute('data-full-name', '埃隆 马斯克')