w3schools dom query code example

Example 1: queryselector function in javascript

/*The querySelector() method returns the first element that matches a specified 
CSS selector(s) in the document. Note: The querySelector() method only returns 
the first element that matches the specified selectors. To return all the 
matches, use the querySelectorAll() method instead.*/

// for example 

//for class
document.querySelector(".ClassName")

// for id 
document.querySelector("#ID")

// etc.

Example 2: dom queryselector

// TO select all the h1 from Html
document.querySelectorAll("h1")

//To select h1 from a particular class or id
document.querySelector(".className/#id h1")