refactor(book-library): apply best practices and style guide

- Rename code variables to descriptive element suffixes
- Optimize render function to clear table efficiently
- Update comments to concise British English

Author: Tarawally

debugging/book-library/script.js

@@ -1,7 +1,7 @@
-const title = document.getElementById("title");
-const author = document.getElementById("author");
-const pages = document.getElementById("pages");
-const check = document.getElementById("check");
+const titleInput = document.getElementById("title");
+const authorInput = document.getElementById("author");
+const pagesInput = document.getElementById("pages");
+const readCheckbox = document.getElementById("check");
 const table = document.getElementById("display");
 const submitBtn = document.getElementById("submit-book-btn");
 
@@ -19,7 +19,7 @@ function populateStorage() {
   if (storedLibrary) {
     myLibrary = JSON.parse(storedLibrary);
   } else {
-    // Default books if nothing in storage
+    // Initialises default books if storage empty
     let book1 = new Book("Robison Crusoe", "Daniel Defoe", "252", true);
     let book2 = new Book(
       "The Old Man and the Sea",
@@ -37,27 +37,29 @@ function saveStorage() {
   localStorage.setItem("myLibrary", JSON.stringify(myLibrary));
 }
 
-//check the right input from forms and if its ok -> add the new book (object in array)
-//via Book function and start render function
+// Validates input and adds new book
 function addBook(e) {
-  // Prevent form submission if we wrap this in a form later,
-  // though currently it's just a button. Good practice.
   if (e) e.preventDefault();
 
-  if (!title.value || !author.value || !pages.value) {
+  if (!titleInput.value || !authorInput.value || !pagesInput.value) {
     alert("Please fill all fields!");
     return false;
   } else {
-    let book = new Book(title.value, author.value, pages.value, check.checked);
+    let book = new Book(
+      titleInput.value,
+      authorInput.value,
+      pagesInput.value,
+      readCheckbox.checked
+    );
     myLibrary.push(book);
     saveStorage();
     render();
 
-    // Clear inputs
-    title.value = "";
-    author.value = "";
-    pages.value = "";
-    check.checked = false;
+    // Clears inputs
+    titleInput.value = "";
+    authorInput.value = "";
+    pagesInput.value = "";
+    readCheckbox.checked = false;
   }
 }
 
@@ -69,54 +71,51 @@ function Book(title, author, pages, check) {
 }
 
 function render() {
-  let rowsNumber = table.rows.length;
-  //delete old table
-  for (let n = rowsNumber - 1; n > 0; n--) {
-    table.deleteRow(n);
-  }
-  //insert updated row and cells
+  // Clears table body efficiently
+  const tbody = table.querySelector("tbody");
+  tbody.innerHTML = "";
+
+  // Inserts updated row and cells
   let length = myLibrary.length;
   for (let i = 0; i < length; i++) {
     // Insert at the end of the table
-    let row = table.insertRow(-1);
+    let row = tbody.insertRow(-1);
     let titleCell = row.insertCell(0);
     let authorCell = row.insertCell(1);
     let pagesCell = row.insertCell(2);
     let wasReadCell = row.insertCell(3);
     let deleteCell = row.insertCell(4);
 
-    // SECURITY: Use textContent to prevent XSS
+    // Uses textContent to prevent XSS
     titleCell.textContent = myLibrary[i].title;
     authorCell.textContent = myLibrary[i].author;
     pagesCell.textContent = myLibrary[i].pages;
 
-    //add and wait for action for read/unread button
-    let changeBut = document.createElement("button");
-    // Removed arbitrary index-based ID
-    changeBut.className = "btn btn-success";
-    wasReadCell.appendChild(changeBut);
+    // Toggles read status
+    let readBtn = document.createElement("button");
+    readBtn.className = "btn btn-success";
+    wasReadCell.appendChild(readBtn);
 
     let readStatus = "";
     if (myLibrary[i].check == false) {
       readStatus = "No";
     } else {
       readStatus = "Yes";
     }
-    changeBut.textContent = readStatus;
+    readBtn.textContent = readStatus;
 
-    changeBut.addEventListener("click", function () {
+    readBtn.addEventListener("click", function () {
       myLibrary[i].check = !myLibrary[i].check;
       saveStorage();
       render();
     });
 
-    //add delete button to every row and render again
-    let delButton = document.createElement("button");
-    // Removed arbitrary index-based ID
-    deleteCell.appendChild(delButton);
-    delButton.className = "btn btn-warning";
-    delButton.textContent = "Delete";
-    delButton.addEventListener("click", function () {
+    // Deletes book
+    let deleteBtn = document.createElement("button");
+    deleteCell.appendChild(deleteBtn);
+    deleteBtn.className = "btn btn-warning";
+    deleteBtn.textContent = "Delete";
+    deleteBtn.addEventListener("click", function () {
       if (confirm(`Are you sure you want to delete: ${myLibrary[i].title}?`)) {
         myLibrary.splice(i, 1);
         saveStorage();