// get "data-qa" value by "id"
var data = document.getElementById('id-test2').getAttribute('data-qa');
console.log(data);

// get "id" value by "data-qa"
var data = document.querySelector('[data-qa="data-qa-test2"]').id;
console.log(data);

// get all elements with attribute "data-qa"
var elems = document.querySelectorAll('[data-qa]');

// get all "ids"
var data = [];
elems.forEach(function(elem){
  data.push(elem.id);
});
console.log(data);

// get all "data-qa"
var data = [];
elems.forEach(function(elem){
  data.push(elem.getAttribute('data-qa'));
});
console.log(data);

// get all "ids" and "data-qa"
var data = [];
elems.forEach(function(elem){
  data.push({
    "id": elem.id,
    "qa": elem.getAttribute('data-qa')
  });
});
console.log(data);

// get all "ids" and "data-qa" with "id" as key
var data = {};
elems.forEach(function(elem){
  data[elem.id] = {
    "id": elem.id,
    "qa": elem.getAttribute('data-qa')
  };
});
console.log(data);

<div id="id-test" data-qa="data-qa-test"></div>
<div id="id-test1" data-qa="data-qa-test1"></div>
<div id="id-test2" data-qa="data-qa-test2"></div>
<div id="id-test3" data-qa="data-qa-test3"></div>

const ids = ["id-test","id-test1","id-test2","id-test3"];

const getData = (id) => document.querySelector(`#${id}`).dataset.qa;

const values = ids.map(id => getData(id));

console.log(values);

<div id="id-test" data-qa="data-qa-test"></div>
<div id="id-test1" data-qa="data-qa-test1"></div>
<div id="id-test2" data-qa="data-qa-test2"></div>
<div id="id-test3" data-qa="data-qa-test3"></div>