# Automatic Canvas Resizing



**Warning:** This method is only enabled when Canvas Height is set to "Fixed at (800)px" in the App Dashboard.

The method **`FB.Canvas.setAutoGrow()`** starts or stops a timer which will grow your iframe to fit the content every few milliseconds. Default timeout is 100ms.

This method was previously called `FB.Canvas.setAutoResize`.

*NOTE:* When using this method, ensure that window.name is not overridden as that can cause issues.

## Examples {#examples}

This function is useful if you know your content will change size, but you don't know when. There will be a slight delay, so if you know when your content changes size, you should call [setSize()](https://developers.facebook.com/documentation/javascript/reference/FB.Canvas.setSize)
yourself (and save your user's CPU cycles).

```
window.fbAsyncInit = function() {
FB.init({
appId: 'YOUR_APP_ID', // App ID
});
FB.Canvas.setAutoGrow();
}
```

If you ever need to stop the timer, just pass false.

```
FB.Canvas.setAutoGrow(false);
```

If you want the timer to run at a different interval, you can do that too.

```
FB.Canvas.setAutoGrow(91); // Paul's favourite number
```

If there is only 1 parameter and it is a number, it is assumed to be the interval.

## Parameters {#params}

| Name | Type | Required | Description |
| --- | --- | --- | --- |
| onOrOff | `boolean` | yes | Whether to turn the timer on or off. truthy ==<br>on, falsy == off. **default** is true |
| interval | `integer` | yes | How often to resize (in ms). **default** is<br>100ms |