---
url: /api/helpers/onResize/functions/onResize.md
---
# onResize()

```ts
function onResize(
  target: HTMLElement,
  callback: (args: {
    size: {
      width: number;
      height: number;
    };
    devicePixelSize: {
      width: number;
      height: number;
    };
    entries: ResizeObserverEntry[];
  }) => void,
): {
  stop: () => void;
  observe: () => void;
  unobserve: () => void;
};
```

Dynamically get the size of an HTML element in CSS pixels and device pixels, and update it on resize events.

## Parameters

### target

`HTMLElement`

### callback

(`args`: {
`size`: {
`width`: `number`;
`height`: `number`;
};
`devicePixelSize`: {
`width`: `number`;
`height`: `number`;
};
`entries`: `ResizeObserverEntry`\[];
}) => `void`

## Returns

| Name          | Type         | Description                         |
| ------------- | ------------ | ----------------------------------- |
| `stop()`      | () => `void` | Disconnect the resize observer.     |
| `observe()`   | () => `void` | Start observing the target element. |
| `unobserve()` | () => `void` | Stop observing the target element.  |