Migration Guide

Learn how to migrate from 0.x to 1.x

Anything before 1.0 is considered a pre-release version and is not guaranteed to be stable. While this guide may not be all encompassing, there were a lot of changes made not only to the library, but to Svelte itself.

The hope is that this information will get you most of the way there, but it's highly encouraged to check the documentation for the components you're using to determine what else may have changed.

Why Migrate?

Bits UI has been completely rewritten from the ground up to support Svelte 5. The rewrite has provided us with a number of benefits in the form of performance improvements, bug fixes, more flexible APIs, and an overall improved developer experience.

Once you learn how to use the new version of Bits UI, we're confident you'll find it to be a much more capable headless component library than before.

Shared Changes

  • The el prop has been replaced with a ref prop across all components that render an HTML element. See the Ref documentation for more information.
  • The asChild prop has been replaced with a child snippet prop across all components that render an HTML element. See the Child Snippet documentation for more information.
  • Components that used to accept transition props no longer do in favor of using the child snippet along with forceMount to use Svelte transitions. See the Transitions documentation for more information.
  • Components that used to provide data via let: directives now provide that data via children/child snippet props.

Accordion

  • The multiple prop has been removed from the Accordion.Root component and replaced with a required type prop which can be set to either 'single' or 'multiple'. This is used as a discriminant to properly type the value prop as either a string or string[].
  • The various transition props have been removed from the Accordion.Content component. See the Transitions documentation for more information.

Alert Dialog

  • The various transition props have been removed from the AlertDialog.Content and AlertDialog.Overlay components. See the Transitions documentation for more information.
  • To render the dialog content in a portal, you now must wrap the AlertDialog.Content in the AlertDialog.Portal component.
  • The AlertDialog.Action component no longer closes the dialog by default, as we learned it was causing more harm than good when attempting to submit a form with the Action button. See the Form Submission section for more information on how to handle submitting forms before closing the dialog.

Button

  • The Button component no longer accepts a builders prop, instead you should use the child snippet on the various components to receive/pass the attributes to the underlying button. See Child Snippet for more information.

Checkbox

  • The Checkbox.Indicator component has been removed in favor of using the children snippet prop to get a reference to the checked state and render a custom indicator. See the Checkbox documentation for more information.
  • The Checkbox.Input component has been removed in favor of automatically rendering a hidden input when the name prop is provided to the Checkbox.Root component.

Combobox

  • The multiple prop has been removed from the Combobox.Root component and replaced with a required type prop which can be set to either 'single' or 'multiple'. This is used as a discriminant to properly type the value prop as either a string or string[].
  • The selected prop has been replaced with a value prop, which is limited to a string (or string[] if type="multiple").
  • The combobox now automatically renders a hidden input when the name prop is provided to the Combobox.Root component.
  • The Combobox.ItemIndicator component has been removed in favor of using the children snippet prop to get a reference to the selected state and render a custom indicator. See the Combobox documentation for more information.
  • Combobox.Group and Combobox.GroupHeading have been added to support groups within the combobox.

Context Menu/Dropdown Menu/Menubar Menu

  • The .RadioIndicator and .CheckboxIndicator components have been removed in favor of using the children snippet prop to get a reference to the checked or selected state and render a custom indicator. See the Context Menu, Dropdown Menu, and Menubar documentation for more information.
  • The .Label component, which was used as the heading for a group of items has been replaced with the .GroupHeading component.
  • The href prop on the .Item components has been removed in favor of the child snippet and rendering your own anchor element.

Pin Input

  • The PinInput component has been overhauled to better act as an OTP input component. See the Pin Input documentation for more information.

Select

  • The multiple prop has been removed from the Select.Root component and replaced with a required type prop which can be set to either 'single' or 'multiple'. This is used as a discriminant to properly type the value prop as either a string or string[].
  • The selected prop has been replaced with a value prop, which is limited to a string (or string[] if type="multiple").
  • The select now automatically renders a hidden input when the name prop is provided to the Select.Root component.
  • The Select.ItemIndicator component has been removed in favor of using the children snippet prop to get a reference to the selected state and render a custom indicator. See the Select documentation for more information.
  • Select.Group and Select.GroupHeading have been added to support groups within the Select.

Tooltip

  • A required component necessary to provide context for shared tooltips, Tooltip.Provider has been added. This replaces the group prop on the previous version's Tooltip component. You can wrap your entire app with Tooltip.Provider, or wrap a specific section of your app with it to provide shared context for tooltips.