//Load a book from disk
                            function loadBook(fileName,displayName){
                                let currentBook = "";
                                let url = "/books/" + fileName;
                            
                                //reset our UI
                                document.getElementById("fileName").innerHTML = displayName;
                                document.getElementById("searchstat").innerHTML = "";
                                document.getElementById("keyword").value = "";
                            
                                //create a server request to load our book
                                var xhr = new XMLHttpRequest();
                                xhr.open("GET", url, true);
                                xhr.send();
                            
                                xhr.onreadystatechange = function () {
                                    if (xhr.readyState == 4 && xhr.status == 200) {
                                        currentBook = xhr.responseText;
                            
                                        getDocStats(currentBook);
                            
                                        //remove line breaks and carriage returns and replace with a 

                                        currentBook = currentBook.replace(/(?:\r\n|\r|\n)/g, '
');
                            
                                        document.getElementById("fileContent").innerHTML = currentBook;
                            
                                        var elmnt = document.getElementById("fileContent");
                                        elmnt.scrolltop = 0;
                                    }
                                };
                            
                            }
                            
                            //get the stats for the book
                            function getDocStats(fileContent) {
                                var docLength = document.getElementById("docLength");
                                var wordCount = document.getElementById("wordCount");
                                var charCount = document.getElementById("charCount");
                            
                                let text = fileContent.toLowerCase();
                                let wordArray = text.match(/\b\S+\b/g);
                                let wordDictionary = {};
                            
                                var uncommonWords = [];
                            
                                //filter out uncommon words
                                uncommonWords = filterStopWords(wordArray);
                            
                                //count every word in wordArray
                                for (let word in uncommonWords) {
                                    let wordValue = uncommonWords[word];
                            
                                    if (wordDictionary[wordValue] > 0) {
                                        wordDictionary[wordValue] += 1;
                                    }
                                    else {
                                        wordDictionary[wordValue] = 1;
                                    }
                                }
                            
                                //sort the array
                                let wordList = sortProperties(wordDictionary);
                            
                                //Return top 5 words
                                var top5Words = wordList.slice(0, 6);
                            
                                //return least5 words
                                var least5Words = wordList.slice(-6, wordList.length);
                            
                                //write to page
                                ULTemplate(top5Words, document.getElementById("mostUsed"));
                                ULTemplate(least5Words, document.getElementById("leastUsed"));
                            
                                docLength.innerText = "Document Length: " + text.length;
                                wordCount.innerText = "Word Count: " + wordArray.length;
                            }
                            
                            function ULTemplate(items, element) {
                                let rowTemplate = document.getElementById('template-ul-items');
                                let templateHTML = rowTemplate.innerHTML;
                                let resultsHTML = "";
                            
                                for (i = 0; i < items.length - 1; i++) {
                                    resultsHTML += templateHTML.replace('{{val}}', items[i][0] + " : " + items[i][1] + " time(s)");
                                }
                            
                                element.innerHTML = resultsHTML;
                            }
                            
                            function sortProperties(obj) {
                                //first convert the obj to array
                                let rtnArray = Object.entries(obj);
                            
                                //Sort the array
                                rtnArray.sort(function (first, second) {
                                    return second[1] - first[1];
                                });
                            
                                return rtnArray;
                            }
                            
                            //a list of stop words we don't want to include in stats
                            function getStopWords() {
                                return ["a", "able", "about", "across", "after", "all", "almost", "also", "am", "among", "an", "and", "any", "are", "as", "at", "be", "because", "been", "but", "by", "can", "cannot", "could", "dear", "did", "do", "does", "either", "else", "ever", "every", "for", "from", "get", "got", "had", "has", "have", "he", "her", "hers", "him", "his", "how", "however", "i", "if", "in", "into", "is", "it", "its", "just", "least", "let", "like", "likely", "may", "me", "might", "most", "must", "my", "neither", "no", "nor", "not", "of", "off", "often", "on", "only", "or", "other", "our", "own", "rather", "said", "say", "says", "she", "should", "since", "so", "some", "than", "that", "the", "their", "them", "then", "there", "these", "they", "this", "tis", "to", "too", "twas", "us", "wants", "was", "we", "were", "what", "when", "where", "which", "while", "who", "whom", "why", "will", "with", "would", "yet", "you", "your", "ain't", "aren't", "can't", "could've", "couldn't", "didn't", "doesn't", "don't", "hasn't", "he'd", "he'll", "he's", "how'd", "how'll", "how's", "i'd", "i'll", "i'm", "i've", "isn't", "it's", "might've", "mightn't", "must've", "mustn't", "shan't", "she'd", "she'll", "she's", "should've", "shouldn't", "that'll", "that's", "there's", "they'd", "they'll", "they're", "they've", "wasn't", "we'd", "we'll", "we're", "weren't", "what'd", "what's", "when'd", "when'll", "when's", "where'd", "where'll", "where's", "who'd", "who'll", "who's", "why'd", "why'll", "why's", "won't", "would've", "wouldn't", "you'd", "you'll", "you're", "you've"];
                            }
                            
                            function filterStopWords(wordArray) {
                                var commonWords = getStopWords();
                                var commonObj = {};
                                var uncommonArray = [];
                            
                                for (i = 0; i < commonWords.length; i++) {
                                    commonObj[commonWords[i].trim()] = true;
                                }
                            
                                for (i = 0; i < wordArray.length; i++) {
                                    word = wordArray[i].trim().toLowerCase();
                                    if (!commonObj[word]) {
                                        uncommonArray.push(word);
                                    }
                                }
                            
                                return uncommonArray;
                            }
                            
                            //highlight the words in search
                            function performMark() {
                                //read keyword
                                var keyword = document.getElementById("keyword").value;
                                var display = document.getElementById("fileContent");
                            
                                var newContent = "";
                            
                                //find all currently marked items
                                let spans = document.querySelectorAll('mark');
                            
                                //
                                for (var i = 0; i < spans.length; i++) {
                                    spans[i].outerHTML = spans[i].innerHTML;
                                }
                            
                                var re = new RegExp(keyword, "gi");
                                var replaceText = "$&"
                                var bookContent = display.innerHTML;
                            
                                //add mark to book content
                                newContent = bookContent.replace(re, replaceText);
                            
                                display.innerHTML = newContent;
                                var count = document.querySelectorAll('mark').length;
                            
                                document.getElementById("searchstat").innerHTML = "found " + count + " matches";
                            
                                if (count > 0) {
                                    var element = document.getElementById("markme");
                                    element.scrollIntoView();
                                }
                            }
                        
                        

The code is structured in six functions.

loadBook

This function gets the fileName and displayName from the selected file. It will load the file text into the display textbox. Special characters, such as carriage return, line feed, and nulls, are removed via a regex match.

getDocStats

This function gets the word count and page count from the loaded book file and displays the results in the stats box.

ULTemplate

This function, via a template, is used to display the stats lines in the most and least used words stat boxes.

sortProperties

This function sorts the words found in the text based on number of times found.

getStopWords

This function returns a list of words not to include in word search count.

filterStopWords

This function sorts the stop words, from retrieved list, from words found in book, to exclude from word count.

performMark

This function works in conjunction with the search box. When entered word is found, this function will highlight the found word.