Thread by @MrAhmadAwais

Crash Course on the .classList() Web API.

Thread 🧵👇

👋Howdy, it's Awais @MrAhmadAwais — Head of Developer Relations at RapidAPI. Google Devs Expert, GitHub Star, DO Navigator.

I've coded 100s of open-source software used by millions of devs. Contributed to NASA’s Mars Helicopter mission. Learn more → Awais.dev/about

👇

If you write code for the Web, there are a large number of Web APIs available.

Web APIs are typically used with JavaScript.

One such API is the .classList() API.

Let's learn how to use it well. 👇

The .classList() API 🧠

The Element.classList is a read-only property that returns a live DOMTokenList collection of the class attributes of the element.

It can be used to manipulate the class list.

The .classList() API 🧠

👨‍💻 Syntax:

// HTML.
<div class="cover"></div>

// JavaScript.
const div = document.querySelector(".cover");

You can access the classList like this:
div.classList;

Returns a DOMTokenList. It's 0th indexed with JS Array objects. Always case-sensitive.

ADD with the .classList() API 🧠

// Add a class.
div.classList.add("colors");

// Add more than one classes.
div.classList.add("colors", "size");

// Spread works!
const classes = ["size", "colors"];
div.classList.add(...classes);

REMOVE with the .classList() API 🧠

// Remove a class.
div.classList.remove("colors");

// Remove many classes.
div.classList.remove("colors", "size");

// Spread works!
const classes = ["size", "colors"];
div.classList.remove(...classes);

TOGGLE with the .classList() API 🧠

// Toggle a class.
div.classList.toggle("colors");

If the "colors" class is present, remove it, if it's not there, add it.

REPLACE with the .classList() API 🧠

// Replace a class.
div.classList.replace("colors", "purple");

This replaces the class "colors" with class "purple".

CHECK with the .classList() API 🧠

// Check if the element has a class.
div.classList.contains("colors");

It returns true or false.

VIEW with the .classList() API 🧠

// View individual classes.
// For this HTML <div class="colors size">
div.classList.item(0); // colors
div.classList.item(1); // size
div.classList.item(2); // null
div.classList[1]; // colors

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