how to read data set in javascript code example

Example 1: html javascript find data attribute

//javascript get html data attribute
<button data-id="1" >Click</button>
<button data-id="2" >Click</button>
<button data-id="3" >Click</button>
const btns=document.querySelectorAll('button[data-id]');
[...btns].forEach(btn => console.log(btn.getAttribute('data-id')))

Example 2: dataset js

for javascript : 
webappData.getAttribute('data-id');
document.querySelector('#elementId').dataset.id = 'value';

for jquery : 
$(element).attr('data-key', 'value');