Sudipta's Blog

Introducing querySelector() and querySelectorAll() on elements in JavaScript

Introducing querySelector() and querySelectorAll() on elements in JavaScript

Sudipta Chakraborty's photo
Sudipta Chakraborty
·

2 min read

Table of contents

I recently learnt about JavaScript so thought why not share my learnings?

I will share how to use the JavaScript querySelector() and querySelectorAll() to find elements based on CSS selectors.

querySelector()

querySelector() is a function that returns an element that matches a CSS selector. Note the querySelector() method only returns the first instance of a selector.

If no matches are found, null is returned.

Let's see how we use querySelector() to select a element in DOM. Select a input field, where the input is given by user and it has an id input-given. We have to select the input element by CSS id-selector.

let userInput = document.querySelector("#input-given");

Assume, there is a button tag which has class submit-btn, we have to select the button element by CSS class-selector.

let submitBtn = document.querySelector(".submit-btn");

querySelectorAll()

querySelectorAll() method, which is defined both on the document object and on element nodes, takes a selector string and returns a NodeList containing all the elements that it matches CSS Selector.

If no element matches, it returns an empty NodeList.

Let's assume there are three input fields for angles of triangle.

<!DOCTYPE html>
<html>
  <body>
    <div>
      <input type="number" class="angles-input" />
      <input type="number" class="angles-input" />
      <input type="number" class="angles-input" />
    </div>
  </body>
</html>

So, We have to select all input fields using CSS class-selector and querySelectorAll() returns a NodeList containing all three input elements.

let inputAngles = document.querySelectorAll(".angles-input");

Hope this post provides you enough interest to use querySelector and querySelectorAll next time you work on DOM manipulation.

If you liked my content, connect with me?

github
linkedin
twitter

JavaScriptBeginner Developers