new-api/.agents/skills/shadcn-ui/vendor/shadcn/rules/base-vs-radix.md

Base vs Radix

API differences between base and radix. Check the base field from npx shadcn@latest info.

Contents

• Composition: asChild vs render
• Button / trigger as non-button element
• Select (items prop, placeholder, positioning, multiple, object values)
• ToggleGroup (type vs multiple)
• Slider (scalar vs array)
• Accordion (type and defaultValue)

---

Composition: asChild (radix) vs render (base)

Radix uses asChild to replace the default element. Base uses render. Don't wrap triggers in extra elements.

Incorrect:

<DialogTrigger>
  <div>
    <Button>Open</Button>
  </div>
</DialogTrigger>

Correct (radix):

<DialogTrigger asChild>
  <Button>Open</Button>
</DialogTrigger>

Correct (base):

<DialogTrigger render={<Button />}>Open</DialogTrigger>

This applies to all trigger and close components: DialogTrigger, SheetTrigger, AlertDialogTrigger, DropdownMenuTrigger, PopoverTrigger, TooltipTrigger, CollapsibleTrigger, DialogClose, SheetClose, NavigationMenuLink, BreadcrumbLink, SidebarMenuButton, Badge, Item.

---

Button / trigger as non-button element (base only)

When render changes an element to a non-button (<a>, <span>), add nativeButton={false}.

Incorrect (base): missing nativeButton={false}.

<Button render={<a href="/docs" />}>Read the docs</Button>

Correct (base):

<Button render={<a href="/docs" />} nativeButton={false}>
  Read the docs
</Button>

Correct (radix):

<Button asChild>
  <a href="/docs">Read the docs</a>
</Button>

Same for triggers whose render is not a Button:

// base.
<PopoverTrigger render={<InputGroupAddon />} nativeButton={false}>
  Pick date
</PopoverTrigger>

---

Select

items prop (base only). Base requires an items prop on the root. Radix uses inline JSX only.

Incorrect (base):

<Select>
  <SelectTrigger><SelectValue placeholder="Select a fruit" /></SelectTrigger>
</Select>

Correct (base):

const items = [
  { label: "Select a fruit", value: null },
  { label: "Apple", value: "apple" },
  { label: "Banana", value: "banana" },
]

<Select items={items}>
  <SelectTrigger>
    <SelectValue />
  </SelectTrigger>
  <SelectContent>
    <SelectGroup>
      {items.map((item) => (
        <SelectItem key={item.value} value={item.value}>{item.label}</SelectItem>
      ))}
    </SelectGroup>
  </SelectContent>
</Select>

Correct (radix):

<Select>
  <SelectTrigger>
    <SelectValue placeholder="Select a fruit" />
  </SelectTrigger>
  <SelectContent>
    <SelectGroup>
      <SelectItem value="apple">Apple</SelectItem>
      <SelectItem value="banana">Banana</SelectItem>
    </SelectGroup>
  </SelectContent>
</Select>

Placeholder. Base uses a { value: null } item in the items array. Radix uses <SelectValue placeholder="...">.

Content positioning. Base uses alignItemWithTrigger. Radix uses position.

// base.
<SelectContent alignItemWithTrigger={false} side="bottom">

// radix.
<SelectContent position="popper">

---

Select — multiple selection and object values (base only)

Base supports multiple, render-function children on SelectValue, and object values with itemToStringValue. Radix is single-select with string values only.

Correct (base — multiple selection):

<Select items={items} multiple defaultValue={[]}>
  <SelectTrigger>
    <SelectValue>
      {(value: string[]) => value.length === 0 ? "Select fruits" : `${value.length} selected`}
    </SelectValue>
  </SelectTrigger>
  ...
</Select>

Correct (base — object values):

<Select defaultValue={plans[0]} itemToStringValue={(plan) => plan.name}>
  <SelectTrigger>
    <SelectValue>{(value) => value.name}</SelectValue>
  </SelectTrigger>
  ...
</Select>

---

ToggleGroup

Base uses a multiple boolean prop. Radix uses type="single" or type="multiple".

Incorrect (base):

<ToggleGroup type="single" defaultValue="daily">
  <ToggleGroupItem value="daily">Daily</ToggleGroupItem>
</ToggleGroup>

Correct (base):

// Single (no prop needed), defaultValue is always an array.
<ToggleGroup defaultValue={["daily"]} spacing={2}>
  <ToggleGroupItem value="daily">Daily</ToggleGroupItem>
  <ToggleGroupItem value="weekly">Weekly</ToggleGroupItem>
</ToggleGroup>

// Multi-selection.
<ToggleGroup multiple>
  <ToggleGroupItem value="bold">Bold</ToggleGroupItem>
  <ToggleGroupItem value="italic">Italic</ToggleGroupItem>
</ToggleGroup>

Correct (radix):

// Single, defaultValue is a string.
<ToggleGroup type="single" defaultValue="daily" spacing={2}>
  <ToggleGroupItem value="daily">Daily</ToggleGroupItem>
  <ToggleGroupItem value="weekly">Weekly</ToggleGroupItem>
</ToggleGroup>

// Multi-selection.
<ToggleGroup type="multiple">
  <ToggleGroupItem value="bold">Bold</ToggleGroupItem>
  <ToggleGroupItem value="italic">Italic</ToggleGroupItem>
</ToggleGroup>

Controlled single value:

// base — wrap/unwrap arrays.
const [value, setValue] = React.useState("normal")
<ToggleGroup value={[value]} onValueChange={(v) => setValue(v[0])}>

// radix — plain string.
const [value, setValue] = React.useState("normal")
<ToggleGroup type="single" value={value} onValueChange={setValue}>

---

Slider

Base accepts a plain number for a single thumb. Radix always requires an array.

Incorrect (base):

<Slider defaultValue={[50]} max={100} step={1} />

Correct (base):

<Slider defaultValue={50} max={100} step={1} />

Correct (radix):

<Slider defaultValue={[50]} max={100} step={1} />

Both use arrays for range sliders. Controlled onValueChange in base may need a cast:

// base.
const [value, setValue] = React.useState([0.3, 0.7])
<Slider value={value} onValueChange={(v) => setValue(v as number[])} />

// radix.
const [value, setValue] = React.useState([0.3, 0.7])
<Slider value={value} onValueChange={setValue} />

---

Accordion

Radix requires type="single" or type="multiple" and supports collapsible. defaultValue is a string. Base uses no type prop, uses multiple boolean, and defaultValue is always an array.

Incorrect (base):

<Accordion type="single" collapsible defaultValue="item-1">
  <AccordionItem value="item-1">...</AccordionItem>
</Accordion>

Correct (base):

<Accordion defaultValue={["item-1"]}>
  <AccordionItem value="item-1">...</AccordionItem>
</Accordion>

// Multi-select.
<Accordion multiple defaultValue={["item-1", "item-2"]}>
  <AccordionItem value="item-1">...</AccordionItem>
  <AccordionItem value="item-2">...</AccordionItem>
</Accordion>

Correct (radix):

<Accordion type="single" collapsible defaultValue="item-1">
  <AccordionItem value="item-1">...</AccordionItem>
</Accordion>