yew/website/versioned_docs/version-0.21/concepts/html/classes.mdx

---
title: 'Classes'
description: 'A handy macro to handle classes'
---

import Tabs from '@theme/Tabs'
import TabItem from '@theme/TabItem'

## Classes

The struct `Classes` can be used to deal with HTML classes.

When pushing a string to the set, `Classes` ensures that there is one element
for every class even if a single string might contain multiple classes.

`Classes` can also be merged by using `Extend` (i.e.
`classes1.extend(classes2)`) or `push()` (i.e. `classes1.push(classes2)`).
Any type that implements `Into<Classes>` can be pushed onto an existing `Classes`.

The macro `classes!` is a convenient macro that creates one single `Classes`.
Its input accepts a comma-separated list of expressions. The only requirement
is that every expression implements `Into<Classes>`.

<Tabs>
  <TabItem value="Literal" label="Literal">

```rust
use yew::{classes, html};

html! {
    <div class={classes!("container")}></div>
};
```

  </TabItem>
  <TabItem value="Multiple" label="Multiple">

```rust
use yew::{classes, html};

html! {
  <div class={classes!("class-1", "class-2")}></div>
};
```

  </TabItem>
  <TabItem value="String" label="String">

```rust
use yew::{classes, html};

let my_classes = String::from("class-1 class-2");

html! {
  <div class={classes!(my_classes)}></div>
};
```

  </TabItem>
  <TabItem value="Optional" label="Optional">

```rust
use yew::{classes, html};

html! {
  <div class={classes!(Some("class"))} />
};
```

  </TabItem>
  <TabItem value="Vector" label="Vector">

```rust
use yew::{classes, html};

html! {
  <div class={classes!(vec!["class-1", "class-2"])}></div>
};
```

  </TabItem>
  <TabItem value="Array" label="Array">

```rust
use yew::{classes, html};

html! {
  <div class={classes!(["class-1", "class-2"])}></div>
};
```

  </TabItem>
</Tabs>

## Components that accept classes

```rust
use yew::prelude::*;

#[derive(PartialEq, Properties)]
struct Props {
    #[prop_or_default]
    class: Classes,
    fill: bool,
    children: Html,
}

#[function_component]
fn MyComponent(props: &Props) -> Html {
    let Props {
        class,
        fill,
        children,
    } = props;
    html! {
        <div
            class={classes!(
                "my-container-class",
                fill.then(|| Some("my-fill-class")),
                class.clone(),
            )}
        >
            { children.clone() }
        </div>
    }
}
```