Finding child element of parent pure javascript

Question

What would the most efficient method be to find a child element of (with class or ID) of a particular parent element using pure javascript only. No jQuery or other framework

Answer 1

You have a parent element, you want to get all child of specific attribute 1. get the parent 2. get the parent nodename by using parent.nodeName.toLowerCase() convert the nodename to lower case e.g DIV will be div 3. for further specific purpose, get an attribute of the parent e.g parent.getAttribute("id"). this will give you id of the parent 4. Then use document.QuerySelectorAll(paret.nodeName.toLowerCase()+"#"_parent.getAttribute("id")+" input " ); if you want input children of the parent node

let parent = document.querySelector("div.classnameofthediv")
let parent_node = parent.nodeName.toLowerCase()
let parent_clas_arr = parent.getAttribute("class").split(" ");
let parent_clas_str = '';
  parent_clas_arr.forEach(e=>{
     parent_clas_str +=e+'.';
  })
let parent_class_name = parent_clas_str.substr(0, parent_clas_str.length-1)  //remove the last dot
let allchild = document.querySelectorAll(parent_node+"."+parent_class_name+" input")