Create your first keyword highlight

Continue with the same core instance from Getting started. In this tutorial, your application already has a set of terms from a policy, review standard, or system configuration. You will pass those terms to Core and highlight every occurrence in the PDF.

Open the Keyword Highlighter demo to review prepared matches, print them, or export a searchable PDF with editable Highlight annotations.

NOTE

Keyword highlights are temporary previews. They do not change the PDF or create saved annotations.

Prepare the keywords

Define the terms your application needs to find. This example uses contract-review terms, but the array could also come from an API or saved system settings:

const contractRiskTerms = [
  'liability',
  'termination',
  'indemnity'
]

Highlight the keywords

Create the Highlighter, pass in the prepared terms, and scan the loaded PDF:

import { createKeywordHighlighter } from '@inklayer-dev/core/highlighter'

const highlighter = createKeywordHighlighter({
  viewer: core.viewer,
  annotations: core.annotations
})

highlighter.setRules([{
  id: 'contract-risks',
  label: 'Contract risks',
  terms: contractRiskTerms,
  color: '#facc15'
}])

await highlighter.scan()

const { matches } = highlighter.getSnapshot()
console.log(`Found ${matches.length} matches`)

if (matches[0]) {
  highlighter.activateMatch(matches[0].id)
}

setRules() accepts the prepared keyword group. scan() finds every occurrence and immediately displays the results as temporary yellow highlights. activateMatch() then moves the Viewer to the first result.

The rule id should remain stable when the same rule is reused. The label is a name your application can show to users, while color controls the preview color.

Highlight prepared structured values

Some review standards define values by shape rather than by a fixed word. If your application already has prepared amount or date patterns, pass them as serializable patterns in exactly the same workflow:

import type { KeywordRule } from '@inklayer-dev/core/highlighter'

const structuredReviewRules: readonly KeywordRule[] = [{
  id: 'structured-values',
  label: 'Dates and amounts',
  color: '#8b5cf6',
  patterns: [
    {
      id: 'iso-date',
      kind: 'regex',
      source: '\\b\\d{4}-\\d{2}-\\d{2}\\b',
      flags: 'u'
    },
    {
      id: 'rmb-amount',
      kind: 'regex',
      source: '(?:¥|RMB\\s*)\\d+(?:,\\d{3})*(?:\\.\\d{2})?',
      flags: 'iu'
    }
  ]
}]

highlighter.setRules(structuredReviewRules)
await highlighter.scan()

Pass the regular-expression source without /.../ delimiters. Keep each pattern id stable just like a rule ID. Core returns the exact PDF text in match.matchedText, so a result list can show RMB 1,200.50 instead of displaying the expression itself. For supported flags, limits, page boundaries, and safety behavior, continue with the complete Keyword Highlighter guide.

Clean up

Release the Highlighter before destroying Core:

highlighter.destroy()
await core.destroy()

You now have a working keyword highlighter driven by application rules. To add multiple colored groups, a result list, review controls, cancellation, or permanent annotations, continue with the complete Keyword Highlighter guide. To turn reviewed matches into an image-only document with no extractable page text, continue with Create your first keyword redaction.