titleCase

title-case.js

function break_into_words( text ) {
  return text.split( ' ' ).filter( function(word) { return word !== ''; } );
}

function add( element, to_array ) {
  to_array.push( element );
}

function space_separated( array ) {
  return array.join( ' ' );
}

String.prototype.in_lower_case = function( ) { return this.toLowerCase(); };

String.prototype.is_one_of_the = function( words ) {
  if ( 'undefined' === typeof words ) {
    words = '';
  }
  
  var words_as_array_in_lowercase = words.split( ' ' ).map( function(word) { return word.in_lower_case(); } );
  return -1 !== words_as_array_in_lowercase.indexOf( this.in_lower_case() );
};

String.prototype.first_letter_capitalized_rest_lowercased = function () {
  return this[0].toUpperCase() + this.slice( 1 ).in_lower_case();
};

function titleCase(title, minorWords) {
  var title_cased_title = '',
    words_in_title = break_into_words( title ),
    case_corrected_words_in_title = [];
    
  words_in_title.forEach( function( word, index ) {
    var this_is_not_the_first_word_in_the_title = index !== 0;
    
    if (
      word.is_one_of_the( minorWords )
      && this_is_not_the_first_word_in_the_title
    ) {
      add( word.in_lower_case(), case_corrected_words_in_title );
    } else {
      add( word.first_letter_capitalized_rest_lowercased(), case_corrected_words_in_title );
    }
  } );
  
  return space_separated( case_corrected_words_in_title );
}