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Overview

The Button component is a fundamental UI element that triggers actions. It’s built using class-variance-authority (CVA) for variant management and supports polymorphic behavior through Radix UI’s Slot component.
Location: src/components/ui/button.tsx

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Implementation

The button component uses CVA to manage variants and sizes: 
import * as React from "react"
import { Slot } from "@radix-ui/react-slot"
import { cva, type VariantProps } from "class-variance-authority"
import { cn } from "@/lib/utils"

const buttonVariants = cva(
  "inline-flex items-center justify-center gap-2 whitespace-nowrap rounded-md text-sm font-medium ring-offset-background transition-colors focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2 disabled:pointer-events-none disabled:opacity-50 [&_svg]:pointer-events-none [&_svg]:size-4 [&_svg]:shrink-0",
  {
    variants: {
      variant: {
        default: "bg-primary text-primary-foreground hover:bg-primary/90",
        destructive: "bg-destructive text-destructive-foreground hover:bg-destructive/90",
        outline: "border border-input bg-background hover:bg-accent hover:text-accent-foreground",
        secondary: "bg-secondary text-secondary-foreground hover:bg-secondary/80",
        ghost: "hover:bg-accent hover:text-accent-foreground",
        link: "text-primary underline-offset-4 hover:underline",
      },
      size: {
        default: "h-10 px-4 py-2",
        sm: "h-9 rounded-md px-3",
        lg: "h-11 rounded-md px-8",
        icon: "h-10 w-10",
      },
    },
    defaultVariants: {
      variant: "default",
      size: "default",
    },
  }
)

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Button Variants

The primary button style with solid background.
<Button variant="default">Save Changes</Button>
Use cases:
  • Primary actions
  • Form submissions
  • Call-to-action buttons

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Button Sizes

// Small button
<Button size="sm">Small</Button>

// Default button
<Button size="default">Default</Button>

// Large button
<Button size="lg">Large</Button>

// Icon-only button (square)
<Button size="icon">
  <Mail className="h-4 w-4" />
</Button>

Small (sm)

  • Height: 36px (h-9)
  • Padding: 12px horizontal
  • Use for compact interfaces

Default

  • Height: 40px (h-10)
  • Padding: 16px horizontal
  • Standard button size

Large (lg)

  • Height: 44px (h-11)
  • Padding: 32px horizontal
  • Use for emphasis

Icon

  • Dimensions: 40x40px
  • Equal width and height
  • Perfect for icon buttons

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Polymorphic Behavior with asChild

The asChild prop allows the button to merge with a child component, useful for navigation: 
import { Button } from "@/components/ui/button"
import { Link } from "react-router-dom"

// Renders as a Link component but looks like a Button
<Button asChild>
  <Link to="/about">About Us</Link>
</Button>

// Renders as an anchor tag
<Button asChild>
  <a href="https://example.com" target="_blank">
    External Link
  </a>
</Button>
Use asChild to maintain proper semantics when a button needs to be a link or other element.

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Button with Icons

The button automatically styles child SVG icons: 
import { Mail, ArrowRight } from "lucide-react"
import { Button } from "@/components/ui/button"

// Icon before text
<Button>
  <Mail className="mr-2 h-4 w-4" />
  Send Email
</Button>

// Icon after text
<Button>
  Continue
  <ArrowRight className="ml-2 h-4 w-4" />
</Button>

// Icon only
<Button size="icon">
  <Mail className="h-4 w-4" />
</Button>

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Real Usage Example

From src/components/ContactSection.tsx: 
import { Linkedin, Globe, Mail } from "lucide-react"

// Primary action with icon
<a
  href="https://www.linkedin.com/in/carrascosa"
  target="_blank"
  rel="noopener noreferrer"
  className="inline-flex items-center gap-3 px-6 py-3 rounded-lg bg-primary text-primary-foreground font-heading font-medium hover:opacity-90 transition-opacity"
>
  <Linkedin className="w-5 h-5" />
  LinkedIn
</a>

// Outline variant for secondary actions
<a
  href="https://www.grupo-sade.com"
  target="_blank"
  rel="noopener noreferrer"
  className="inline-flex items-center gap-3 px-6 py-3 rounded-lg border border-border text-foreground font-heading font-medium hover:border-primary/50 transition-colors"
>
  <Globe className="w-5 h-5" />
  Grupo SADE
</a>

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Accessibility Features

The button component includes built-in accessibility features:
  • Focus Visible: Clear focus ring on keyboard navigation
  • Disabled State: Proper disabled styling and pointer events
  • ARIA Support: Works with standard button ARIA attributes
// Disabled button
<Button disabled>Cannot Click</Button>

// With ARIA label
<Button aria-label="Close dialog" size="icon">
  <X className="h-4 w-4" />
</Button>

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Customization

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Custom Styles

<Button className="rounded-full font-bold uppercase tracking-wider">
  Custom Styled
</Button>

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New Variant

Extend the buttonVariants: 
import { buttonVariants } from "@/components/ui/button"
import { cn } from "@/lib/utils"

export function SuccessButton({ children, className, ...props }) {
  return (
    <button
      className={cn(
        buttonVariants({ variant: "default" }),
        "bg-green-600 hover:bg-green-700",
        className
      )}
      {...props}
    >
      {children}
    </button>
  )
}

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TypeScript Interface

export interface ButtonProps
  extends React.ButtonHTMLAttributes<HTMLButtonElement>,
    VariantProps<typeof buttonVariants> {
  asChild?: boolean
}
The interface extends:
  • Native button HTML attributes
  • CVA variant props (variant and size)
  • Custom asChild prop for polymorphism

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Best Practices

Do

  • Use semantic variants (destructive for delete)
  • Include descriptive text or aria-label
  • Use appropriate sizes for context
  • Leverage asChild for navigation

Don't

  • Don’t use multiple primary buttons
  • Avoid vague labels like “Click Here”
  • Don’t disable without explanation
  • Don’t override core accessibility
  • Cards - Container components for content
  • Forms - Form components with validation
  • Animations - Animation patterns for buttons

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