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React's __register__ classNamesperform the same function as classes in JavaScript. They are used instead of classes because class__register__ is a reserved word in React.

Adding multiple to a component classNamesgives us room to set some conditions for that component. One classNameis for styling; the other is for setting the condition.

This is ideal when we create a web page with buttons.

Additionally, we may want to add additional styles to a component to override the original styles in certain situations. Adding an additional classNamewill allow us to do this smoothly.

Furthermore, using multiple classNameto set styles makes the CSS file easier to read, track, and adjust, as a single <div> classNamemay be overloaded with too many styles. Also, in cases where multiple CSS classes have similar properties, we should create another class for the similar properties to facilitate corrections and additional components.

Let's look at classNamesdifferent ways to add multiple to a component.

Template literals, also known as template strings, allow users to create and manipulate multiple expressions enclosed in backticks followed by $a ampersand and curly braces.

We will create a button webpage example that shows classNamesthe effect of multiple buttons while using CSS styles. Navigate to the file in our project folder App.jsand write the following code:

Code Snippet- App.js:

import React from "react";
import "./App.css";
export default function App() {
  const [classNames, setClassNames] = React.useState(``);
  const [showRed, setShowRed] = React.useState(false);
  const [showBlue, setShowBlue] = React.useState(false);
  React.useEffect(() => {
    setClassNames(`${showRed ? "red" : ""} ${showBlue ? "blue" : ""}`);
  }, [showRed, showBlue]);
  return (
    <div>
      <button onClick={() => setShowRed(showRed => !showRed)}>
        Toggle Red
      </button>
      <button onClick={() => setShowBlue(showBlue => !showBlue)}>
        Toggle Light Blue
      </button>
      <div className={classNames}>hit me!</div>
    </div>
  );
}

setClassNamesTemplate literals classNamesare handy for holding when we call the function. This is where we set the classes redand respectively blue.

We will then App.cssdo some coding in the file:

Code Snippet- App.css:

.red {
  color: red;
}.blue {
  background-color: lightblue;
  width: 50px;
}

Output:

We use button onClickevent listeners to tell React what to do when either button is clicked. When we click one of the buttons, we can see that one classNameis activated, and when we click the other button, the other classNameis called and the color changes.

One of the reasons for React's widespread acceptance is that it has unlimited potential for development and tweaking due to its dependencies.

classnamesPackages are classNamesanother method we can use to add multiple <div> to a component. It helps us write less code than the template literal method and classNamesworks better when dealing with more than two <div> .

Once the project folder is created, we will navigate to the project folder while still inside and install classnamesthe package:

$ npm install classnames

Then, we start coding, App.jsstarting with the files.

We use the same styles as in the first example. We won't repeat the CSS snippet here.

Code Snippet- App.js:

import React from "react";
import "./App.css";
const classNames = require("classnames");

export default function App() {
  const [showRed, setShowRed] = React.useState(false);
  const [showBlue, setShowBlue] = React.useState(false); return (
    <div>
      <button onClick={() => setShowRed(showRed => !showRed)}>
        Toggle Red
      </button>
      <button onClick={() => setShowBlue(showBlue => !showBlue)}>
        Toggle Light Blue
      </button>
      <div className={classNames({ red: showRed, blue: showBlue })}>
        hello
      </div>
    </div>
  );
}

Output:

classnamesThe package is applied and wrapped in divwhere we set the for each component classNamesand then we use onClickevent listeners to change the state of each class.

When we click on any of the buttons assigned to a class, we can see each one classNamebeing turned on/off.

If we want to apply the same style to multiple classes at the same time, we can use the classnames package and .mapthe method. .mapA method is a JavaScript function that helps us pass functions between similar elements.

Once we have the project folder created, we will navigate to the project folder while still inside, and we will install classnamesthe package:

$ npm install classnames

Next, we start coding; first, use App.jsthe file:

Code Snippet- App.js:

import React from "react";
import "./App.css";
const classNames = require("classnames");

export default function App() {
  const [showRed, setShowRed] = React.useState(false);
  return (
    <div>
      {["foo", "bar", "baz"].map(buttonType => (
        <button
          className={classNames({ [`btn-${buttonType}`]: showRed })}
          onClick={() => setShowRed(showRed => !showRed)}
        >
          Button {buttonType}
        </button>
      ))}
    </div>
  );
}

After declaring our classNames, .mapthe function maps all three classes to buttonTypeobjects. This will allow us to pass the same function across multiple classes.

Then, our App.csswill look like this:

.btn-foo,
.btn-bar,
.btn-baz {
  color: red;
}

Output:

We assigned the same color to all the classes and when we toggle any button, onClickthe event listener activates this CSS function.

Using multiple classes in React allows us to try different combinations, so we have different ways to get around obstacles. And because it enables us to perform multiple styles and conditions in one component, coding is more flexible and we can detect errors and bugs with precision.