How to add a word counter to a content block in Sanity?

For displaying a word counter on a content block, you don't necessarily need to create a fully custom field type. The best approach depends on whether you want the counter to be read-only or interactive.

For a read-only word counter (most common use case), you can use the components property on your field schema to add a custom React component that calculates and displays the count. This is simpler than creating a full custom input component.

Here's a practical example:

import {Stack, Text} from '@sanity/ui'

const WordCounter = (props) => {
  const {renderDefault, value} = props
  
  // Calculate word count from your content
  const wordCount = value ? value.split(/\s+/).filter(Boolean).length : 0
  
  return (
    <Stack space={3}>
      {renderDefault(props)}
      <Text size={1} muted>
        Word count: {wordCount}
      </Text>
    </Stack>
  )
}

// In your schema
{
  name: 'content',
  type: 'text', // or 'string'
  components: {
    input: WordCounter
  }
}

For Portable Text/Block Content, you'll need to extract text from the blocks array:

const countWordsInBlocks = (blocks) => {
  if (!blocks) return 0
  return blocks
    .filter(block => block._type === 'block')
    .map(block => block.children?.map(child => child.text).join(' ') || '')
    .join(' ')
    .split(/\s+/)
    .filter(Boolean).length
}

If you need more complex functionality (like setting word count limits or warnings), then creating a custom input component gives you full control over the rendering and behavior.

The components.input approach is generally preferred for simple enhancements like counters because it:

• Wraps the existing input (less code to maintain)
• Preserves all default Studio functionality
• Is easier to implement and update

You can also use Component Views to display document-level statistics in a separate tab, but that's more useful for overall document analytics rather than per-field counters.