Highlight text in a string of content

highlightMatch.js

// Used to match HTML entities and HTML characters.
const unescapedHtml = /[&<>"']/g
const hasUnescapedHtml = RegExp(unescapedHtml.source)
const htmlEscapes = {
  "&": "&amp",
  "<": "&lt",
  ">": "&gt",
  '"': "&quot",
  "'": "&#39"
}
/* Converts the characters "&", "<", ">", '"', & "'" in `string` to their corresponding HTML entities */
function escapeString(str) {
  return str && hasUnescapedHtml.test(str)
    ? str.replace(unescapedHtml, (character) => htmlEscapes[character])
    : str
}

function highlightMatch(text, originalContent) {
  var content = escapeString(originalContent)
  var index = content.indexOf(text)
  if (index >= 0) {
    content =
      content.substring(0, index) +
      "<mark>" +
      content.substring(index, index + text.length) +
      "</mark>" +
      content.substring(index + text.length)
    return content
  }
  return originalContent
}