to-title-case.js

/* To Title Case © 2018 David Gouch | https://github.com/gouch/to-title-case */

// eslint-disable-next-line no-extend-native
String.prototype.toTitleCase = function () {
  'use strict'
  var smallWords = /^(a|an|and|as|at|but|by|en|for|if|in|nor|of|on|or|per|the|to|v.?|vs.?|via)$/i
  var alphanumericPattern = /([A-Za-z0-9\u00C0-\u00FF])/
  var wordSeparators = /([ :–—-])/

  return this.split(wordSeparators)
    .map(function (current, index, array) {
      if (
        /* Check for small words */
        current.search(smallWords) > -1 &&
        /* Skip first and last word */
        index !== 0 &&
        index !== array.length - 1 &&
        /* Ignore title end and subtitle start */
        array[index - 3] !== ':' &&
        array[index + 1] !== ':' &&
        /* Ignore small words that start a hyphenated phrase */
        (array[index + 1] !== '-' ||
          (array[index - 1] === '-' && array[index + 1] === '-'))
      ) {
        return current.toLowerCase()
      }

      /* Ignore intentional capitalization */
      if (current.substr(1).search(/[A-Z]|\../) > -1) {
        return current
      }

      /* Ignore URLs */
      if (array[index + 1] === ':' && array[index + 2] !== '') {
        return current
      }

      /* Capitalize the first letter */
      return current.replace(alphanumericPattern, function (match) {
        return match.toUpperCase()
      })
    })
    .join('')
}