client/src/app/header/highlight.pipe.ts

   1 import { PipeTransform, Pipe } from '@angular/core'
   2 import { SafeHtml } from '@angular/platform-browser'
   3
   4 // Thanks https://gist.github.com/adamrecsko/0f28f474eca63e0279455476cc11eca7#gistcomment-2917369
   5 @Pipe({ name: 'highlight' })
   6 export class HighlightPipe implements PipeTransform {
   7   /* use this for single match search */
   8   static SINGLE_MATCH = 'Single-Match'
   9   /* use this for single match search with a restriction that target should start with search string */
  10   static SINGLE_AND_STARTS_WITH_MATCH = 'Single-And-StartsWith-Match'
  11   /* use this for global search */
  12   static MULTI_MATCH = 'Multi-Match'
  13
  14   transform (
  15     contentString: string = null,
  16     stringToHighlight: string = null,
  17     option = 'Single-And-StartsWith-Match',
  18     caseSensitive = false,
  19     highlightStyleName = 'search-highlight'
  20   ): SafeHtml {
  21     if (stringToHighlight && contentString && option) {
  22       let regex: any = ''
  23       const caseFlag: string = !caseSensitive ? 'i' : ''
  24
  25       switch (option) {
  26         case 'Single-Match': {
  27           regex = new RegExp(stringToHighlight, caseFlag)
  28           break
  29         }
  30         case 'Single-And-StartsWith-Match': {
  31           regex = new RegExp('^' + stringToHighlight, caseFlag)
  32           break
  33         }
  34         case 'Multi-Match': {
  35           regex = new RegExp(stringToHighlight, 'g' + caseFlag)
  36           break
  37         }
  38         default: {
  39           // default will be a global case-insensitive match
  40           regex = new RegExp(stringToHighlight, 'gi')
  41         }
  42       }
  43
  44       const replaced = contentString.replace(
  45         regex,
  46         (match) => `<span class="${highlightStyleName}">${match}</span>`
  47       )
  48
  49       return replaced
  50     } else {
  51       return contentString
  52     }
  53   }
  54 }