55. highlight keywords in HTML string

Suppose you are implementing an auto-complete in search input.

When keywords are typed, you need to highlight the keywords, how would you do that?

To simplify things, you need to create a function highlightKeywords(html:string, keywords: string[]), which wraps the keywords in html string, with <em> tag.

Here is an example.

highlightKeywords(
  'Hello FrontEnd Lovers', 
  ['Hello', 'Front', 'JavaScript']
)
// '<em>Hello</em> <em>Front</em>End Lovers'

Pay attention to the overlapping and adjacent case. You should use the least tags as possible.

highlightKeywords(
  'Hello FrontEnd Lovers', 
  ['Front', 'End', 'JavaScript']
)
// 'Hello <em>FrontEnd</em> Lovers'

highlightKeywords(
  'Hello FrontEnd Lovers', 
  ['Front', 'FrontEnd', 'JavaScript']
)
// 'Hello <em>FrontEnd</em> Lovers'

note that space should not be included.