Answers for "how to select first child in js of id"

first child element javascript

Both these will give you the first child node:

console.log(parentElement.firstChild); // or
console.log(parentElement.childNodes[0]);

If you need the first child that is an element node then use:

console.log(parentElement.children[0]);

firstElementChild jquery equivalent

$('#myList > li:first-child');
// or
$('#myList').children('li:first-child');
// or
$('#myList > li').first();
// or
$('#myList').children().first();
// and so on