Как редактировать элемент массива с помощью javascript

// Open
const openModal = function() {
  document.querySelector("#my-modal").style.display = "block";
}


  // Close
const closeModal = function() {
  document.querySelector("#my-modal").style.display = "none";
}

function initModal() {
  const modal = document.querySelector("#my-modal");
  const closeBtn = document.querySelector(".close");

  // Events
  closeBtn.addEventListener("click", closeModal);
  window.addEventListener("click", outsideClick);


  // Close If Outside Click
  function outsideClick(e) {
    if (e.target == modal) {
      modal.style.display = "none";
    }
  }
}

const filters = []; // dummy variable

// Generate the DOM structure for a todo
var todos = []
function generateTodoDOM(todo) {
  todos.push(todo);
  const todoEl = document.createElement("div");
  const checkbox = document.createElement("input");
  const label = document.createElement("label");
  checkbox.appendChild(label);
  todoEl.setAttribute("id", "my-todos-" + todo.id);
  const textEl = document.createElement("p");
  const editButton = document.createElement("button");
  editButton.setAttribute("id", "modal-btn-" + todo.id);
  const removeButton = document.createElement("button");
  const createDate = document.createElement("p");
  createDate.textContent = 'Created: ' + new Date();
  createDate.style.color = "#956E93";

  // Setup the todo text
  textEl.textContent = todo.text;
  todoEl.appendChild(textEl);

  // Setup the remove button
  removeButton.textContent = "x";
  todoEl.appendChild(removeButton);
  removeButton.addEventListener("click", function() {
    removeTodo(todo.id);
    saveTodos(todos);
    renderTodos(todos, filters);
  });

  // TODO: Setup the edit note button
  editButton.textContent = "Edit Todo";
  todoEl.appendChild(editButton);
  editButton.addEventListener("click", function() {
    //Launch the modal
    editModal(todo.id);
    openModal();
  });
  // Setup todo checkbox
  checkbox.setAttribute("type", "checkbox");
  checkbox.checked = todo.completed;
  todoEl.appendChild(checkbox);
  checkbox.addEventListener("change", function() {
    toggleTodo(todo.id);
    saveTodos(todos);
    renderTodos(todos, filters);
  });

  todoEl.appendChild(createDate);

  return todoEl;
};


var editFn
//Edit modal todo by id
const editModal = function(id) {
  const todoIndex = todos.findIndex(function(todo) {
    return todo.id === id;
  });
  if (todoIndex > -1) {
    const modal = document.querySelector("#my-modal");
    const editElm = document.querySelector("#editTodo");
    const editTodoContentBtn = document.querySelector("#submitEditTodo")

    editElm.value = todos[todoIndex].text;

    // Events
    editTodoContentBtn.removeEventListener("click", editFn)

    //Edit the content of the textarea
    editFn = function(e) {
      editTodo(id)
      closeModal()
    }

    editTodoContentBtn.addEventListener("click", editFn)

  }
};


//Edit todo by id
const editTodo = function(id) {
  const editTodoContent = document.querySelector('#editTodo')
  const todoIndex = todos.findIndex(function(todo) {
    return todo.id === id;
  });

  if (todoIndex > -1) {
    todos[todoIndex].text = editTodoContent.value;
    saveTodos(todos)
    renderTodos(todos, filters);
  }
};

const saveTodos = function(todos) {
  // dummy method, we're keeping it in memory for this example
}

const renderTodos = function(todosToRender) {
  todos = []; // clear current in-memory array
  var todoList = document.getElementById("todo-container");
  while (todoList.firstChild) {
      todoList.removeChild(todoList.firstChild);
  }
  for(var i = 0; i < todosToRender.length; i++) {
    todoList.appendChild(generateTodoDOM(todosToRender[i]));
  }
};


initModal();
const container = document.getElementById("todo-container");
var generatedTodos = [];
for(var i = 0; i < 10; i++) {
  var todo = { text: "Todo " + (i+1), id: "todo-" + i, completed: false};
  generatedTodos.push(todo);
}
renderTodos(generatedTodos);

/*
Edit todo modal start
*/

:root {
  --modal-duration: 1s;
  --modal-color: #BB8AB8;
}

.modal {
  display: none;
  position: fixed;
  z-index: 1;
  left: 0;
  top: 0;
  height: 100%;
  width: 100%;
  overflow: auto;
  background-color: rgba(0, 0, 0, 0.5);
}

.modal-content {
  margin: 10% auto;
  width: 35%;
  box-shadow: 0 5px 8px 0 rgba(0, 0, 0, 0.2), 0 7px 20px 0 rgba(0, 0, 0, 0.17);
  animation-name: modalopen;
  animation-duration: var(--modal-duration);
}

.editTextArea{
  width:100%
}

.modal-header h2,
.modal-footer h3 {
  margin: 0;
}

.modal-header {
  background: var(--modal-color);
  padding: 15px;
  color: #fff;
  border-top-left-radius: 5px;
  border-top-right-radius: 5px;
}

.modal-body {
  padding: 10px 20px;
  background: #fff;
}

.modal-footer {
  background: var(--modal-color);
  padding: 10px;
  color: #fff;
  text-align: center;
  border-bottom-left-radius: 5px;
  border-bottom-right-radius: 5px;
}

.close {
  color: #ccc;
  float: right;
  font-size: 30px;
  color: #fff;
}

.close:hover,
.close:focus {
  color: #000;
  text-decoration: none;
  cursor: pointer;
}

@keyframes modalopen {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

/*
Edit todo modal end
*/

<!DOCTYPE html>
<html>
<head>
	<link rel = "stylesheet" href = "style.css">
</head>
<body>
	<div id = "todo-container">

	</div>
	<!-- Edit modal -->
  <div id = "my-modal" class = "modal">
    <div class = "modal-content">
      <div class = "modal-header">
        <span class = "close">&times;</span>
        <h2>Edit Todo</h2>
      </div>
      <div class = "modal-body">
        <textarea name = "" class = "editTextArea" id = "editTodo"  rows = "10"></textarea>
        <button class = "button" id = "submitEditTodo">Edit Todo</button>
      </div>
      <div class = "modal-footer">
        <!-- <h3>Modal Footer</h3> -->
      </div>
    </div>
   </div>
   <!-- End modal --> 
</body>
</html>