<div class="box">
<div class="parent">
<div class="child">1</div>
<div class="child">2</div>
<div class="child">3</div>
</div>
<hr>
<div class="parent">
<div class="child">10</div>
<div class="child">20</div>
<div class="child">30</div>
</div>
<hr>
<div class="parent">
<div class="child">5</div>
<div class="child">10</div>
<div class="child">15</div>
</div>
</div>
<script>
let arr = [4, 40, 20];
for(let i = 0; i < arr.length; i++) {
$('.parent').append(
'<div class="child">' + arr[i] + '</div>'
);
}
</script>
<div class="box">
<div class="parent">
<div class="child">1</div>
<div class="child">2</div>
<div class="child">3</div>
<div class="child">4</div>
</div>
<hr>
<div class="parent">
<div class="child">10</div>
<div class="child">20</div>
<div class="child">30</div>
<div class="child">40</div>
</div>
<hr>
<div class="parent">
<div class="child">5</div>
<div class="child">10</div>
<div class="child">15</div>
<div class="child">20</div>
</div>
</div>
const containers = document.querySelectorAll('.parent');
const tag = 'div';
const className = 'child';
containers.forEach((n, i) => {
n.insertAdjacentHTML(
'beforeend',
`<${tag} class="${className}">${arr[i]}</${tag}>`
);
});
// или
for (const [ i, n ] of containers.entries()) {
n.append(Object.assign(document.createElement(tag), {
className,
innerText: arr[i],
}));
}
// или
for (let i = 0; i < containers.length; i++) {
const el = document.createElement(tag);
el.classList.add(className);
el.textContent = arr[i];
containers[i].insertAdjacentElement('beforeend', el);
}
// или
(function add(i, n = containers.item(i)) {
if (n) {
n.appendChild(document.createElement(tag));
n.lastChild.setAttribute('class', className);
n.lastChild.insertBefore(new Text(arr[i]), null);
add(-~i);
}
})(0);