Highlight Transform service

Adds HTML to a string to highlight chosen sections.

Class members

Methods

• highlight(text: string, search: string, wrapperClass: string = "highlight"): HighlightTransformResult
  Searches for search string(s) within text and highlights all occurrences.
  • text: string - Text to search within
  • search: string - Text pattern to search for
  • wrapperClass: string - CSS class used to provide highlighting style
  • Returns HighlightTransformResult - New text along with boolean value to indicate whether anything was highlighted

Details

A typical use case for this service is to display the results from a search engine. An excerpt of a retrieved document can be shown with the matching search terms highlighted to indicate where they were found.

The service works by adding HTML <span> elements around all sections of text that match the search string. You can specify multiple search strings at once by separating them with spaces, so passing "Apple Banana Cherry" in search will highlight any of those words individually. The <span> element includes a class attribute which defaults to "highlight" but you can pass any class name you like using the wrapperClass parameter.

The resulting text with HTML highlighting is returned within a HighlightTransformResult object:

interface HighlightTransformResult {
    text: string;
    changed: boolean;
}

The changed flag will be false if the search string was not found (ie, no highlighting took place) and true otherwise.

See also

• Text highlight pipe
• Highlight directive