const attrName = 'data-i';
const attrValues = [ 'qwe', 'asd', 'zxc' ];
const className = 'класс';
document
.querySelectorAll(attrValues.map(n => `[${attrName}="${n}"]`))
.forEach(n => n.classList.add(className));
for (const n of document.querySelectorAll(`[${attrName}]`)) {
n.classList.toggle(className, attrValues.includes(n.getAttribute(attrName)));
}